A dataset represents an SQL query. Datasets can be used to select, insert, update and delete records.
Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):
my_posts = DB[:posts].where(author: 'david') # no records are retrieved my_posts.all # records are retrieved my_posts.all # records are retrieved again
Datasets are frozen and use a functional style where modification methods return modified copies of the the dataset. This allows you to reuse datasets:
posts = DB[:posts] davids_posts = posts.where(author: 'david') old_posts = posts.where{stamp < Date.today - 7} davids_old_posts = davids_posts.where{stamp < Date.today - 7}
Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.
For more information, see the "Dataset Basics" guide.
OPTS | = | Sequel::OPTS | ||
TRUE_FREEZE | = | RUBY_VERSION >= '2.4' | Whether Dataset#freeze can actually freeze datasets. True only on ruby 2.4+, as it requires clone(freeze: false) | |
STREAMING_SUPPORTED | = | ::Mysql2::VERSION >= '0.3.12' | ||
PreparedStatementMethods | = | prepared_statements_module( "sql = self; opts = Hash[opts]; opts[:arguments] = bind_arguments", Sequel::Dataset::UnnumberedArgumentMapper, %w"execute execute_dui execute_insert") |
Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.
# File lib/sequel/adapters/mysql.rb, line 281 281: def fetch_rows(sql) 282: execute(sql) do |r| 283: i = -1 284: cps = db.conversion_procs 285: cols = r.fetch_fields.map do |f| 286: # Pretend tinyint is another integer type if its length is not 1, to 287: # avoid casting to boolean if convert_tinyint_to_bool is set. 288: type_proc = f.type == 1 && cast_tinyint_integer?(f) ? cps[2] : cps[f.type] 289: [output_identifier(f.name), type_proc, i+=1] 290: end 291: self.columns = cols.map(&:first) 292: if opts[:split_multiple_result_sets] 293: s = [] 294: yield_rows(r, cols){|h| s << h} 295: yield s 296: else 297: yield_rows(r, cols){|h| yield h} 298: end 299: end 300: self 301: end
# File lib/sequel/adapters/mysql2.rb, line 236 236: def fetch_rows(sql) 237: execute(sql) do |r| 238: self.columns = r.fields.map!{|c| output_identifier(c.to_s)} 239: r.each(:cast_booleans=>convert_tinyint_to_bool?){|h| yield h} 240: end 241: self 242: end
Don‘t allow graphing a dataset that splits multiple statements
# File lib/sequel/adapters/mysql.rb, line 304 304: def graph(*) 305: raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets] 306: super 307: end
Makes each yield arrays of rows, with each array containing the rows for a given result set. Does not work with graphing. So you can submit SQL with multiple statements and easily determine which statement returned which results.
Modifies the row_proc of the returned dataset so that it still works as expected (running on the hashes instead of on the arrays of hashes). If you modify the row_proc afterward, note that it will receive an array of hashes instead of a hash.
# File lib/sequel/adapters/mysql.rb, line 318 318: def split_multiple_result_sets 319: raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph] 320: ds = clone(:split_multiple_result_sets=>true) 321: ds = ds.with_row_proc(proc{|x| x.map{|h| row_proc.call(h)}}) if row_proc 322: ds 323: end
cache | [R] | Access the cache for the current dataset. Should be used with caution, as access to the cache is not thread safe without a mutex if other threads can reference the dataset. Symbol keys prefixed with an underscore are reserved for internal use. |
db | [R] | The database related to this dataset. This is the Database instance that will execute all of this dataset‘s queries. |
opts | [R] | The hash of options for this dataset, keys are symbols. |
Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:
DB[:posts]
Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.
# File lib/sequel/dataset/misc.rb, line 25 25: def initialize(db) 26: @db = db 27: @opts = OPTS 28: @cache = {} 29: freeze 30: end
Return self, as datasets are always frozen.
# File lib/sequel/dataset/misc.rb, line 50 50: def dup 51: self 52: end
Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:
DB[:configs].where(key: 'setting').each_server{|ds| ds.update(value: 'new_value')}
# File lib/sequel/dataset/misc.rb, line 59 59: def each_server 60: db.servers.each{|s| yield server(s)} 61: end
Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:
ds.escape_like("foo\\%_") # 'foo\\\%\_'
# File lib/sequel/dataset/misc.rb, line 68 68: def escape_like(string) 69: string.gsub(/[\\%_]/){|m| "\\#{m}"} 70: end
Alias of first_source_alias
# File lib/sequel/dataset/misc.rb, line 91 91: def first_source 92: first_source_alias 93: end
The first source (primary table) for this dataset. If the dataset doesn‘t have a table, raises an Error. If the table is aliased, returns the aliased name.
DB[:table].first_source_alias # => :table DB[Sequel[:table].as(:t)].first_source_alias # => :t
# File lib/sequel/dataset/misc.rb, line 103 103: def first_source_alias 104: source = @opts[:from] 105: if source.nil? || source.empty? 106: raise Error, 'No source specified for query' 107: end 108: case s = source.first 109: when SQL::AliasedExpression 110: s.alias 111: when Symbol 112: _, _, aliaz = split_symbol(s) 113: aliaz ? aliaz.to_sym : s 114: else 115: s 116: end 117: end
The first source (primary table) for this dataset. If the dataset doesn‘t have a table, raises an error. If the table is aliased, returns the original table, not the alias
DB[:table].first_source_table # => :table DB[Sequel[:table].as(:t)].first_source_table # => :table
# File lib/sequel/dataset/misc.rb, line 128 128: def first_source_table 129: source = @opts[:from] 130: if source.nil? || source.empty? 131: raise Error, 'No source specified for query' 132: end 133: case s = source.first 134: when SQL::AliasedExpression 135: s.expression 136: when Symbol 137: sch, table, aliaz = split_symbol(s) 138: aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s 139: else 140: s 141: end 142: end
Freeze the opts when freezing the dataset.
# File lib/sequel/dataset/misc.rb, line 74 74: def freeze 75: @opts.freeze 76: super 77: end
Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.
# File lib/sequel/dataset/misc.rb, line 176 176: def split_alias(c) 177: case c 178: when Symbol 179: c_table, column, aliaz = split_symbol(c) 180: [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz] 181: when SQL::AliasedExpression 182: [c.expression, c.alias] 183: when SQL::JoinClause 184: [c.table, c.table_alias] 185: else 186: [c, nil] 187: end 188: end
This returns an SQL::Identifier or SQL::AliasedExpression containing an SQL identifier that represents the unqualified column for the given value. The given value should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression containing one of those. In other cases, this returns nil.
# File lib/sequel/dataset/misc.rb, line 195 195: def unqualified_column_for(v) 196: unless v.is_a?(String) 197: _unqualified_column_for(v) 198: end 199: end
Creates a unique table alias that hasn‘t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with "_N" if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.
You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.
DB[:table].unused_table_alias(:t) # => :t DB[:table].unused_table_alias(:table) # => :table_0 DB[:table, :table_0].unused_table_alias(:table) # => :table_1 DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2]) # => :table_3
# File lib/sequel/dataset/misc.rb, line 223 223: def unused_table_alias(table_alias, used_aliases = []) 224: table_alias = alias_symbol(table_alias) 225: used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from] 226: used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join] 227: if used_aliases.include?(table_alias) 228: i = 0 229: while true 230: ta = "#{table_alias}_#{i}""#{table_alias}_#{i}" 231: return ta unless used_aliases.include?(ta) 232: i += 1 233: end 234: else 235: table_alias 236: end 237: end
Set a value in the dataset‘s cache in a thread safe manner.
# File lib/sequel/dataset/misc.rb, line 258 258: def cache_set(k, v) 259: Sequel.synchronize{@cache[k] = v} 260: end
Clear the columns hash for the current dataset. This is not a thread safe operation, so it should only be used if the dataset could not be used by another thread (such as one that was just created via clone).
# File lib/sequel/dataset/misc.rb, line 266 266: def clear_columns_cache 267: @cache.delete(:_columns) 268: end
These methods all execute the dataset‘s SQL on the database. They don‘t return modified datasets, so if used in a method chain they should be the last method called.
ACTION_METHODS | = | (<<-METHS).split.map(&:to_sym).freeze << [] all as_hash avg count columns columns! delete each empty? fetch_rows first first! get import insert last map max min multi_insert paged_each select_hash select_hash_groups select_map select_order_map single_record single_record! single_value single_value! sum to_hash to_hash_groups truncate update where_all where_each where_single_value METHS ).split.map(&:to_sym).freeze | Action methods defined by Sequel that execute code on the database. | |
COLUMNS_CLONE_OPTIONS | = | {:distinct => nil, :limit => 1, :offset=>nil, :where=>nil, :having=>nil, :order=>nil, :row_proc=>nil, :graph=>nil, :eager_graph=>nil}.freeze | The clone options to use when retriveing columns for a dataset. | |
COUNT_SELECT | = | Sequel.function(:count).*.as(:count) | ||
EMPTY_SELECT | = | Sequel::SQL::AliasedExpression.new(1, :one) |
Inserts the given argument into the database. Returns self so it can be used safely when chaining:
DB[:items] << {id: 0, name: 'Zero'} << DB[:old_items].select(:id, name)
# File lib/sequel/dataset/actions.rb, line 29 29: def <<(arg) 30: insert(arg) 31: self 32: end
Returns the first record matching the conditions. Examples:
DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1 # => {:id=>1}
# File lib/sequel/dataset/actions.rb, line 38 38: def [](*conditions) 39: raise(Error, 'You cannot call Dataset#[] with an integer or with no arguments') if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0 40: first(*conditions) 41: end
Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.
DB[:table].all # SELECT * FROM table # => [{:id=>1, ...}, {:id=>2, ...}, ...] # Iterate over all rows in the table DB[:table].all{|row| p row}
# File lib/sequel/dataset/actions.rb, line 51 51: def all(&block) 52: _all(block){|a| each{|r| a << r}} 53: end
Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].as_hash(:id, :name) # SELECT * FROM table # {1=>'Jim', 2=>'Bob', ...} DB[:table].as_hash(:id) # SELECT * FROM table # {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].as_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table # {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...} DB[:table].as_hash([:id, :name]) # SELECT * FROM table # {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob']=>{:id=>2, :name=>'Bob'}, ...}
Options:
:all : | Use all instead of each to retrieve the objects |
:hash : | The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc. |
# File lib/sequel/dataset/actions.rb, line 765 765: def as_hash(key_column, value_column = nil, opts = OPTS) 766: h = opts[:hash] || {} 767: meth = opts[:all] ? :all : :each 768: if value_column 769: return naked.as_hash(key_column, value_column, opts) if row_proc 770: if value_column.is_a?(Array) 771: if key_column.is_a?(Array) 772: public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)} 773: else 774: public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)} 775: end 776: else 777: if key_column.is_a?(Array) 778: public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]} 779: else 780: public_send(meth){|r| h[r[key_column]] = r[value_column]} 781: end 782: end 783: elsif key_column.is_a?(Array) 784: public_send(meth){|r| h[key_column.map{|k| r[k]}] = r} 785: else 786: public_send(meth){|r| h[r[key_column]] = r} 787: end 788: h 789: end
Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1 # => 3 DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 62 62: def avg(arg=Sequel.virtual_row(&Proc.new)) 63: _aggregate(:avg, arg) 64: end
Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.
If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.
DB[:table].columns # => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 75 75: def columns 76: _columns || columns! 77: end
Ignore any cached column information and perform a query to retrieve a row in order to get the columns.
DB[:table].columns! # => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 84 84: def columns! 85: ds = clone(COLUMNS_CLONE_OPTIONS) 86: ds.each{break} 87: 88: if cols = ds.cache[:_columns] 89: self.columns = cols 90: else 91: [] 92: end 93: end
Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.
DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1 # => 3 DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1 # => 2 DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 108 108: def count(arg=(no_arg=true), &block) 109: if no_arg && !block 110: cached_dataset(:_count_ds) do 111: aggregate_dataset.select(COUNT_SELECT).single_value_ds 112: end.single_value!.to_i 113: else 114: if block 115: if no_arg 116: arg = Sequel.virtual_row(&block) 117: else 118: raise Error, 'cannot provide both argument and block to Dataset#count' 119: end 120: end 121: 122: _aggregate(:count, arg) 123: end 124: end
Deletes the records in the dataset, returning the number of records deleted.
DB[:table].delete # DELETE * FROM table # => 3
# File lib/sequel/dataset/actions.rb, line 130 130: def delete(&block) 131: sql = delete_sql 132: if uses_returning?(:delete) 133: returning_fetch_rows(sql, &block) 134: else 135: execute_dui(sql) 136: end 137: end
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
DB[:table].each{|row| p row} # SELECT * FROM table
Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each.
# File lib/sequel/dataset/actions.rb, line 148 148: def each 149: if rp = row_proc 150: fetch_rows(select_sql){|r| yield rp.call(r)} 151: else 152: fetch_rows(select_sql){|r| yield r} 153: end 154: self 155: end
Returns true if no records exist in the dataset, false otherwise
DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1 # => false
# File lib/sequel/dataset/actions.rb, line 163 163: def empty? 164: cached_dataset(:_empty_ds) do 165: single_value_ds.unordered.select(EMPTY_SELECT) 166: end.single_value!.nil? 167: end
Returns the first matching record if no arguments are given. If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If any other type of argument(s) is passed, it is treated as a filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.
If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).
Examples:
DB[:table].first # SELECT * FROM table LIMIT 1 # => {:id=>7} DB[:table].first(2) # SELECT * FROM table LIMIT 2 # => [{:id=>6}, {:id=>4}] DB[:table].first(id: 2) # SELECT * FROM table WHERE (id = 2) LIMIT 1 # => {:id=>2} DB[:table].first(Sequel.lit("id = 3")) # SELECT * FROM table WHERE (id = 3) LIMIT 1 # => {:id=>3} DB[:table].first(Sequel.lit("id = ?", 4)) # SELECT * FROM table WHERE (id = 4) LIMIT 1 # => {:id=>4} DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1 # => {:id=>5} DB[:table].first(Sequel.lit("id > ?", 4)){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1 # => {:id=>5} DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2 # => [{:id=>1}]
# File lib/sequel/dataset/actions.rb, line 204 204: def first(*args, &block) 205: case args.length 206: when 0 207: unless block 208: return single_record 209: end 210: when 1 211: arg = args[0] 212: if arg.is_a?(Integer) 213: res = if block 214: if loader = cached_placeholder_literalizer(:_first_integer_cond_loader) do |pl| 215: where(pl.arg).limit(pl.arg) 216: end 217: 218: loader.all(filter_expr(&block), arg) 219: else 220: where(&block).limit(arg).all 221: end 222: else 223: if loader = cached_placeholder_literalizer(:_first_integer_loader) do |pl| 224: limit(pl.arg) 225: end 226: 227: loader.all(arg) 228: else 229: limit(arg).all 230: end 231: end 232: 233: return res 234: end 235: args = arg 236: end 237: 238: if loader = cached_placeholder_literalizer(:_first_cond_loader) do |pl| 239: _single_record_ds.where(pl.arg) 240: end 241: 242: loader.first(filter_expr(args, &block)) 243: else 244: _single_record_ds.where(args, &block).single_record! 245: end 246: end
Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.
# File lib/sequel/dataset/actions.rb, line 250 250: def first!(*args, &block) 251: first(*args, &block) || raise(Sequel::NoMatchingRow.new(self)) 252: end
Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.
DB[:table].get(:id) # SELECT id FROM table LIMIT 1 # => 3 ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1 # => 6
You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:
DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1 # => [3, 'foo'] DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1 # => [6, 'foo']
# File lib/sequel/dataset/actions.rb, line 272 272: def get(column=(no_arg=true; nil), &block) 273: ds = naked 274: if block 275: raise(Error, 'Must call Dataset#get with an argument or a block, not both') unless no_arg 276: ds = ds.select(&block) 277: column = ds.opts[:select] 278: column = nil if column.is_a?(Array) && column.length < 2 279: else 280: case column 281: when Array 282: ds = ds.select(*column) 283: when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression 284: if loader = cached_placeholder_literalizer(:_get_loader) do |pl| 285: ds.single_value_ds.select(pl.arg) 286: end 287: 288: return loader.get(column) 289: end 290: 291: ds = ds.select(column) 292: else 293: if loader = cached_placeholder_literalizer(:_get_alias_loader) do |pl| 294: ds.single_value_ds.select(Sequel.as(pl.arg, :v)) 295: end 296: 297: return loader.get(column) 298: end 299: 300: ds = ds.select(Sequel.as(column, :v)) 301: end 302: end 303: 304: if column.is_a?(Array) 305: if r = ds.single_record 306: r.values_at(*hash_key_symbols(column)) 307: end 308: else 309: ds.single_value 310: end 311: end
Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction.
This method is called with a columns array and an array of value arrays:
DB[:table].import([:x, :y], [[1, 2], [3, 4]]) # INSERT INTO table (x, y) VALUES (1, 2) # INSERT INTO table (x, y) VALUES (3, 4)
This method also accepts a dataset instead of an array of value arrays:
DB[:table].import([:x, :y], DB[:table2].select(:a, :b)) # INSERT INTO table (x, y) SELECT a, b FROM table2
Options:
:commit_every : | Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records. |
:return : | When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. |
:server : | Set the server/shard to use for the transaction and insert queries. |
:slice : | Same as :commit_every, :commit_every takes precedence. |
# File lib/sequel/dataset/actions.rb, line 338 338: def import(columns, values, opts=OPTS) 339: return @db.transaction{insert(columns, values)} if values.is_a?(Dataset) 340: 341: return if values.empty? 342: raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty? 343: ds = opts[:server] ? server(opts[:server]) : self 344: 345: if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice)) 346: offset = 0 347: rows = [] 348: while offset < values.length 349: rows << ds._import(columns, values[offset, slice_size], opts) 350: offset += slice_size 351: end 352: rows.flatten 353: else 354: ds._import(columns, values, opts) 355: end 356: end
Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that the a single row is inserted and the table has an autoincrementing primary key.
insert handles a number of different argument formats:
no arguments or single empty hash : | Uses DEFAULT VALUES |
single hash : | Most common format, treats keys as columns and values as values |
single array : | Treats entries as values, with no columns |
two arrays : | Treats first array as columns, second array as values |
single Dataset : | Treats as an insert based on a selection from the dataset given, with no columns |
array and dataset : | Treats as an insert based on a selection from the dataset given, with the columns given by the array. |
Examples:
DB[:items].insert # INSERT INTO items DEFAULT VALUES DB[:items].insert({}) # INSERT INTO items DEFAULT VALUES DB[:items].insert([1,2,3]) # INSERT INTO items VALUES (1, 2, 3) DB[:items].insert([:a, :b], [1,2]) # INSERT INTO items (a, b) VALUES (1, 2) DB[:items].insert(a: 1, b: 2) # INSERT INTO items (a, b) VALUES (1, 2) DB[:items].insert(DB[:old_items]) # INSERT INTO items SELECT * FROM old_items DB[:items].insert([:a, :b], DB[:old_items]) # INSERT INTO items (a, b) SELECT * FROM old_items
# File lib/sequel/dataset/actions.rb, line 394 394: def insert(*values, &block) 395: sql = insert_sql(*values) 396: if uses_returning?(:insert) 397: returning_fetch_rows(sql, &block) 398: else 399: execute_insert(sql) 400: end 401: end
Reverses the order and then runs first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.
DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1 # => {:id=>10} DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2 # => [{:id=>1}, {:id=>2}]
# File lib/sequel/dataset/actions.rb, line 413 413: def last(*args, &block) 414: raise(Error, 'No order specified') unless @opts[:order] 415: reverse.first(*args, &block) 416: end
Maps column values for each record in the dataset (if an argument is given) or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.
DB[:table].map(:id) # SELECT * FROM table # => [1, 2, 3, ...] DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table # => [2, 4, 6, ...]
You can also provide an array of column names:
DB[:table].map([:id, :name]) # SELECT * FROM table # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
# File lib/sequel/dataset/actions.rb, line 432 432: def map(column=nil, &block) 433: if column 434: raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block 435: return naked.map(column) if row_proc 436: if column.is_a?(Array) 437: super(){|r| r.values_at(*column)} 438: else 439: super(){|r| r[column]} 440: end 441: else 442: super(&block) 443: end 444: end
Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1 # => 10 DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1 # => 7
# File lib/sequel/dataset/actions.rb, line 453 453: def max(arg=Sequel.virtual_row(&Proc.new)) 454: _aggregate(:max, arg) 455: end
Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.
DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1 # => 1 DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1 # => 0
# File lib/sequel/dataset/actions.rb, line 464 464: def min(arg=Sequel.virtual_row(&Proc.new)) 465: _aggregate(:min, arg) 466: end
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:
DB[:table].multi_insert([{x: 1}, {x: 2}]) # INSERT INTO table (x) VALUES (1) # INSERT INTO table (x) VALUES (2)
Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.
This respects the same options as import.
# File lib/sequel/dataset/actions.rb, line 480 480: def multi_insert(hashes, opts=OPTS) 481: return if hashes.empty? 482: columns = hashes.first.keys 483: import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts) 484: end
Yields each row in the dataset, but interally uses multiple queries as needed to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.
Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to work correctly, the dataset must have unambiguous order. Using an ambiguous order can result in an infinite loop, as well as subtler bugs such as yielding duplicate rows or rows being skipped.
Sequel checks that the datasets using this method have an order, but it cannot ensure that the order is unambiguous.
Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, use a separate thread or shard inside paged_each.
Options:
:rows_per_fetch : | The number of rows to fetch per query. Defaults to 1000. |
:strategy : | The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and none of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used. |
:filter_values : | If the strategy: :filter option is used, this option should be a proc that accepts the last retreived row for the previous page and an array of ORDER BY expressions, and returns an array of values relating to those expressions for the last retrieved row. You will need to use this option if your ORDER BY expressions are not simple columns, if they contain qualified identifiers that would be ambiguous unqualified, if they contain any identifiers that are aliased in SELECT, and potentially other cases. |
Examples:
DB[:table].order(:id).paged_each{|row| } # SELECT * FROM table ORDER BY id LIMIT 1000 # SELECT * FROM table ORDER BY id LIMIT 1000 OFFSET 1000 # ... DB[:table].order(:id).paged_each(:rows_per_fetch=>100){|row| } # SELECT * FROM table ORDER BY id LIMIT 100 # SELECT * FROM table ORDER BY id LIMIT 100 OFFSET 100 # ... DB[:table].order(:id).paged_each(strategy: :filter){|row| } # SELECT * FROM table ORDER BY id LIMIT 1000 # SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000 # ... DB[:table].order(:id).paged_each(strategy: :filter, filter_values: lambda{|row, exprs| [row[:id]]}){|row| } # SELECT * FROM table ORDER BY id LIMIT 1000 # SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000 # ...
# File lib/sequel/dataset/actions.rb, line 541 541: def paged_each(opts=OPTS) 542: unless @opts[:order] 543: raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered" 544: end 545: unless block_given? 546: return enum_for(:paged_each, opts) 547: end 548: 549: total_limit = @opts[:limit] 550: offset = @opts[:offset] 551: if server = @opts[:server] 552: opts = Hash[opts] 553: opts[:server] = server 554: end 555: 556: rows_per_fetch = opts[:rows_per_fetch] || 1000 557: strategy = if offset || total_limit 558: :offset 559: else 560: opts[:strategy] || :offset 561: end 562: 563: db.transaction(opts) do 564: case strategy 565: when :filter 566: filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}} 567: base_ds = ds = limit(rows_per_fetch) 568: while ds 569: last_row = nil 570: ds.each do |row| 571: last_row = row 572: yield row 573: end 574: ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row) 575: end 576: else 577: offset ||= 0 578: num_rows_yielded = rows_per_fetch 579: total_rows = 0 580: 581: while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit) 582: if total_limit && total_rows + rows_per_fetch > total_limit 583: rows_per_fetch = total_limit - total_rows 584: end 585: 586: num_rows_yielded = 0 587: limit(rows_per_fetch, offset).each do |row| 588: num_rows_yielded += 1 589: total_rows += 1 if total_limit 590: yield row 591: end 592: 593: offset += rows_per_fetch 594: end 595: end 596: end 597: 598: self 599: end
Returns a hash with key_column values as keys and value_column values as values. Similar to as_hash, but only selects the columns given. Like as_hash, it accepts an optional :hash parameter, into which entries will be merged.
DB[:table].select_hash(:id, :name) # SELECT id, name FROM table # => {1=>'a', 2=>'b', ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table # {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine.
# File lib/sequel/dataset/actions.rb, line 617 617: def select_hash(key_column, value_column, opts = OPTS) 618: _select_hash(:as_hash, key_column, value_column, opts) 619: end
Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given. Like to_hash_groups, it accepts an optional :hash parameter, into which entries will be merged.
DB[:table].select_hash_groups(:name, :id) # SELECT id, name FROM table # => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].select_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table # {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}
When using this method, you must be sure that each expression has an alias that Sequel can determine.
# File lib/sequel/dataset/actions.rb, line 636 636: def select_hash_groups(key_column, value_column, opts = OPTS) 637: _select_hash(:to_hash_groups, key_column, value_column, opts) 638: end
Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.
DB[:table].select_map(:id) # SELECT id FROM table # => [3, 5, 8, 1, ...] DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table # => [6, 10, 16, 2, ...]
You can also provide an array of column names:
DB[:table].select_map([:id, :name]) # SELECT id, name FROM table # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.
# File lib/sequel/dataset/actions.rb, line 659 659: def select_map(column=nil, &block) 660: _select_map(column, false, &block) 661: end
The same as select_map, but in addition orders the array by the column.
DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id # => [1, 2, 3, 4, ...] DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2) # => [2, 4, 6, 8, ...]
You can also provide an array of column names:
DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name # => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.
# File lib/sequel/dataset/actions.rb, line 678 678: def select_order_map(column=nil, &block) 679: _select_map(column, true, &block) 680: end
Limits the dataset to one record, and returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method. Example:
DB[:test].single_record # SELECT * FROM test LIMIT 1 # => {:column_name=>'value'}
# File lib/sequel/dataset/actions.rb, line 688 688: def single_record 689: _single_record_ds.single_record! 690: end
Returns the first record in dataset, without limiting the dataset. Returns nil if the dataset has no records. Users should probably use first instead of this method. This should only be used if you know the dataset is already limited to a single record. This method may be desirable to use for performance reasons, as it does not clone the receiver. Example:
DB[:test].single_record! # SELECT * FROM test # => {:column_name=>'value'}
# File lib/sequel/dataset/actions.rb, line 700 700: def single_record! 701: with_sql_first(select_sql) 702: end
Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method. Example:
DB[:test].single_value # SELECT * FROM test LIMIT 1 # => 'value'
# File lib/sequel/dataset/actions.rb, line 710 710: def single_value 711: single_value_ds.each do |r| 712: r.each{|_, v| return v} 713: end 714: nil 715: end
Returns the first value of the first record in the dataset, without limiting the dataset. Returns nil if the dataset is empty. Users should generally use get instead of this method. Should not be used on graphed datasets or datasets that have row_procs that don‘t return hashes. This method may be desirable to use for performance reasons, as it does not clone the receiver.
DB[:test].single_value! # SELECT * FROM test # => 'value'
# File lib/sequel/dataset/actions.rb, line 725 725: def single_value! 726: with_sql_single_value(select_sql) 727: end
Returns the sum for the given column/expression. Uses a virtual row block if no column is given.
DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1 # => 55 DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1 # => 10
# File lib/sequel/dataset/actions.rb, line 736 736: def sum(arg=Sequel.virtual_row(&Proc.new)) 737: _aggregate(:sum, arg) 738: end
Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.
DB[:table].to_hash_groups(:name, :id) # SELECT * FROM table # {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...} DB[:table].to_hash_groups(:name) # SELECT * FROM table # {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}
You can also provide an array of column names for either the key_column, the value column, or both:
DB[:table].to_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table # {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...} DB[:table].to_hash_groups([:first, :middle]) # SELECT * FROM table # {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}
Options:
:all : | Use all instead of each to retrieve the objects |
:hash : | The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc. |
# File lib/sequel/dataset/actions.rb, line 820 820: def to_hash_groups(key_column, value_column = nil, opts = OPTS) 821: h = opts[:hash] || {} 822: meth = opts[:all] ? :all : :each 823: if value_column 824: return naked.to_hash_groups(key_column, value_column, opts) if row_proc 825: if value_column.is_a?(Array) 826: if key_column.is_a?(Array) 827: public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)} 828: else 829: public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)} 830: end 831: else 832: if key_column.is_a?(Array) 833: public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]} 834: else 835: public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]} 836: end 837: end 838: elsif key_column.is_a?(Array) 839: public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r} 840: else 841: public_send(meth){|r| (h[r[key_column]] ||= []) << r} 842: end 843: h 844: end
Truncates the dataset. Returns nil.
DB[:table].truncate # TRUNCATE table # => nil
# File lib/sequel/dataset/actions.rb, line 850 850: def truncate 851: execute_ddl(truncate_sql) 852: end
Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.
DB[:table].update(x: nil) # UPDATE table SET x = NULL # => 10 DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0 # => 10
# File lib/sequel/dataset/actions.rb, line 863 863: def update(values=OPTS, &block) 864: sql = update_sql(values) 865: if uses_returning?(:update) 866: returning_fetch_rows(sql, &block) 867: else 868: execute_dui(sql) 869: end 870: end
Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.
DB[:table].where_all(id: [1,2,3]) # SELECT * FROM table WHERE (id IN (1, 2, 3))
# File lib/sequel/dataset/actions.rb, line 878 878: def where_all(cond, &block) 879: if loader = _where_loader 880: loader.all(filter_expr(cond), &block) 881: else 882: where(cond).all(&block) 883: end 884: end
Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.
DB[:table].where_each(id: [1,2,3]){|row| p row} # SELECT * FROM table WHERE (id IN (1, 2, 3))
# File lib/sequel/dataset/actions.rb, line 892 892: def where_each(cond, &block) 893: if loader = _where_loader 894: loader.each(filter_expr(cond), &block) 895: else 896: where(cond).each(&block) 897: end 898: end
Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.
DB[:table].select(:name).where_single_value(id: 1) # SELECT name FROM table WHERE (id = 1) LIMIT 1
# File lib/sequel/dataset/actions.rb, line 907 907: def where_single_value(cond) 908: if loader = cached_placeholder_literalizer(:_where_single_value_loader) do |pl| 909: single_value_ds.where(pl.arg) 910: end 911: 912: loader.get(filter_expr(cond)) 913: else 914: where(cond).single_value 915: end 916: end
Run the given SQL and return an array of all rows. If a block is given, each row is yielded to the block after all rows are loaded. See with_sql_each.
# File lib/sequel/dataset/actions.rb, line 920 920: def with_sql_all(sql, &block) 921: _all(block){|a| with_sql_each(sql){|r| a << r}} 922: end
Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It‘s significantly faster as it does not require cloning the current dataset.
# File lib/sequel/dataset/actions.rb, line 927 927: def with_sql_delete(sql) 928: execute_dui(sql) 929: end
Run the given SQL and yield each returned row to the block.
# File lib/sequel/dataset/actions.rb, line 933 933: def with_sql_each(sql) 934: if rp = row_proc 935: _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)} 936: else 937: _with_sql_dataset.fetch_rows(sql){|r| yield r} 938: end 939: self 940: end
Run the given SQL and return the first row, or nil if no rows were returned. See with_sql_each.
# File lib/sequel/dataset/actions.rb, line 944 944: def with_sql_first(sql) 945: with_sql_each(sql){|r| return r} 946: nil 947: end
Run the given SQL and return the first value in the first row, or nil if no rows were returned. For this to make sense, the SQL given should select only a single value. See with_sql_each.
# File lib/sequel/dataset/actions.rb, line 952 952: def with_sql_single_value(sql) 953: if r = with_sql_first(sql) 954: r.each{|_, v| return v} 955: end 956: end
Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.
# File lib/sequel/dataset/actions.rb, line 969 969: def _import(columns, values, opts) 970: trans_opts = Hash[opts].merge!(:server=>@opts[:server]) 971: if opts[:return] == :primary_key 972: @db.transaction(trans_opts){values.map{|v| insert(columns, v)}} 973: else 974: stmts = multi_insert_sql(columns, values) 975: @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}} 976: end 977: end
Return an array of arrays of values given by the symbols in ret_cols.
# File lib/sequel/dataset/actions.rb, line 980 980: def _select_map_multiple(ret_cols) 981: map{|r| r.values_at(*ret_cols)} 982: end
On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the "Prepared Statements/Bound Variables" guide.
PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('?').freeze |
DEFAULT_PREPARED_STATEMENT_MODULE_METHODS | = | %w'execute execute_dui execute_insert'.freeze.each(&:freeze) |
PREPARED_STATEMENT_MODULE_CODE | = | { :bind => "opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze, :prepare => "sql = prepared_statement_name".freeze, :prepare_bind => "sql = prepared_statement_name; opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze |
Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.
DB[:table].where(id: :$id).bind(id: 1).call(:first) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 275 275: def bind(bind_vars=OPTS) 276: bind_vars = if bv = @opts[:bind_vars] 277: Hash[bv].merge!(bind_vars).freeze 278: else 279: if bind_vars.frozen? 280: bind_vars 281: else 282: Hash[bind_vars] 283: end 284: end 285: 286: clone(:bind_vars=>bind_vars) 287: end
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.
DB[:table].where(id: :$id).call(:first, id: 1) # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1) # => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 296 296: def call(type, bind_variables=OPTS, *values, &block) 297: to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block) 298: end
Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement.
This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated Database, where it can be called by name. The following usage is identical:
ps = DB[:table].where(name: :$name).prepare(:first, :select_by_name) ps.call(name: 'Blah') # SELECT * FROM table WHERE name = ? -- ('Blah') # => {:id=>1, :name=>'Blah'} DB.call(:select_by_name, name: 'Blah') # Same thing
# File lib/sequel/dataset/prepared_statements.rb, line 316 316: def prepare(type, name, *values) 317: ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true) 318: ps.prepared_sql 319: db.set_prepared_statement(name, ps) 320: ps 321: end
Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.
# File lib/sequel/dataset/prepared_statements.rb, line 327 327: def to_prepared_statement(type, values=nil, opts=OPTS) 328: mods = opts[:extend] || [] 329: mods += [PreparedStatementMethods] 330: 331: bind. 332: clone(:prepared_statement_name=>opts[:name], :prepared_type=>type, :prepared_modify_values=>values, :orig_dataset=>self, :no_cache_sql=>true, :prepared_args=>@opts[:prepared_args]||[], :no_delayed_evaluations=>opts[:no_delayed_evaluations]). 333: with_extend(*mods) 334: end
Returns an EXISTS clause for the dataset as an SQL::PlaceholderLiteralString.
DB.select(1).where(DB[:items].exists) # SELECT 1 WHERE (EXISTS (SELECT * FROM items))
# File lib/sequel/dataset/sql.rb, line 14 14: def exists 15: SQL::PlaceholderLiteralString.new(EXISTS, [self], true) 16: end
Returns an INSERT SQL query string. See insert.
DB[:items].insert_sql(a: 1) # => "INSERT INTO items (a) VALUES (1)"
# File lib/sequel/dataset/sql.rb, line 22 22: def insert_sql(*values) 23: return static_sql(@opts[:sql]) if @opts[:sql] 24: 25: check_modification_allowed! 26: 27: columns = [] 28: 29: case values.size 30: when 0 31: return insert_sql(OPTS) 32: when 1 33: case vals = values[0] 34: when Hash 35: values = [] 36: vals.each do |k,v| 37: columns << k 38: values << v 39: end 40: when Dataset, Array, LiteralString 41: values = vals 42: end 43: when 2 44: if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString)) 45: columns, values = v0, v1 46: raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length 47: end 48: end 49: 50: if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 51: columns, values = insert_empty_columns_values 52: elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert) 53: ds, values = hoist_cte(values) 54: return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql) 55: end 56: clone(:columns=>columns, :values=>values).send(:_insert_sql) 57: end
Append a literal representation of a value to the given SQL string.
If an unsupported object is given, an Error is raised.
# File lib/sequel/dataset/sql.rb, line 62 62: def literal_append(sql, v) 63: case v 64: when Symbol 65: if skip_symbol_cache? 66: literal_symbol_append(sql, v) 67: else 68: unless l = db.literal_symbol(v) 69: l = String.new 70: literal_symbol_append(l, v) 71: db.literal_symbol_set(v, l) 72: end 73: sql << l 74: end 75: when String 76: case v 77: when LiteralString 78: sql << v 79: when SQL::Blob 80: literal_blob_append(sql, v) 81: else 82: literal_string_append(sql, v) 83: end 84: when Integer 85: sql << literal_integer(v) 86: when Hash 87: literal_hash_append(sql, v) 88: when SQL::Expression 89: literal_expression_append(sql, v) 90: when Float 91: sql << literal_float(v) 92: when BigDecimal 93: sql << literal_big_decimal(v) 94: when NilClass 95: sql << literal_nil 96: when TrueClass 97: sql << literal_true 98: when FalseClass 99: sql << literal_false 100: when Array 101: literal_array_append(sql, v) 102: when Time 103: v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v) 104: when DateTime 105: literal_datetime_append(sql, v) 106: when Date 107: sql << literal_date(v) 108: when Dataset 109: literal_dataset_append(sql, v) 110: else 111: literal_other_append(sql, v) 112: end 113: end
Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.
# File lib/sequel/dataset/sql.rb, line 118 118: def multi_insert_sql(columns, values) 119: case multi_insert_sql_strategy 120: when :values 121: sql = LiteralString.new('VALUES ') 122: expression_list_append(sql, values.map{|r| Array(r)}) 123: [insert_sql(columns, sql)] 124: when :union 125: c = false 126: sql = LiteralString.new 127: u = ' UNION ALL SELECT ' 128: f = empty_from_sql 129: values.each do |v| 130: if c 131: sql << u 132: else 133: sql << 'SELECT ' 134: c = true 135: end 136: expression_list_append(sql, v) 137: sql << f if f 138: end 139: [insert_sql(columns, sql)] 140: else 141: values.map{|r| insert_sql(columns, r)} 142: end 143: end
Same as select_sql, not aliased directly to make subclassing simpler.
# File lib/sequel/dataset/sql.rb, line 146 146: def sql 147: select_sql 148: end
Returns a TRUNCATE SQL query string. See truncate
DB[:items].truncate_sql # => 'TRUNCATE items'
# File lib/sequel/dataset/sql.rb, line 153 153: def truncate_sql 154: if opts[:sql] 155: static_sql(opts[:sql]) 156: else 157: check_truncation_allowed! 158: check_not_limited!(:truncate) 159: raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having] 160: t = String.new 161: source_list_append(t, opts[:from]) 162: _truncate_sql(t) 163: end 164: end
Formats an UPDATE statement using the given values. See update.
DB[:items].update_sql(price: 100, category: 'software') # => "UPDATE items SET price = 100, category = 'software'
Raises an Error if the dataset is grouped or includes more than one table.
# File lib/sequel/dataset/sql.rb, line 173 173: def update_sql(values = OPTS) 174: return static_sql(opts[:sql]) if opts[:sql] 175: check_modification_allowed! 176: check_not_limited!(:update) 177: 178: case values 179: when LiteralString 180: # nothing 181: when String 182: raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string" 183: end 184: 185: clone(:values=>values).send(:_update_sql) 186: end
These methods, while public, are not designed to be used directly by the end user.
WILDCARD | = | LiteralString.new('*').freeze |
COUNT_OF_ALL_AS_COUNT | = | SQL::Function.new(:count, WILDCARD).as(:count) |
DEFAULT | = | LiteralString.new('DEFAULT').freeze |
EXISTS | = | ['EXISTS '.freeze].freeze |
BITWISE_METHOD_MAP | = | {:& =>:BITAND, :| => :BITOR, :^ => :BITXOR}.freeze |
COUNT_FROM_SELF_OPTS | = | [:distinct, :group, :sql, :limit, :offset, :compounds].freeze |
IS_LITERALS | = | {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze |
QUALIFY_KEYS | = | [:select, :where, :having, :order, :group].freeze |
IS_OPERATORS | = | ::Sequel::SQL::ComplexExpression::IS_OPERATORS |
LIKE_OPERATORS | = | ::Sequel::SQL::ComplexExpression::LIKE_OPERATORS |
N_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS |
TWO_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS |
REGEXP_OPERATORS | = | ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS |
Define a dataset literalization method for the given type in the given module, using the given clauses.
Arguments:
mod : | Module in which to define method |
type : | Type of SQL literalization method to create, either :select, :insert, :update, or :delete |
clauses : | array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch. |
# File lib/sequel/dataset/sql.rb, line 209 209: def self.def_sql_method(mod, type, clauses) 210: priv = type == :update || type == :insert 211: cacheable = type == :select || type == :delete 212: 213: lines = [] 214: lines << 'private' if priv 215: lines << "def #{'_' if priv}#{type}_sql" 216: lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv 217: lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable 218: lines << 'check_modification_allowed!' << 'check_not_limited!(:delete)' if type == :delete 219: lines << 'sql = @opts[:append_sql] || sql_string_origin' 220: 221: if clauses.all?{|c| c.is_a?(Array)} 222: clauses.each do |i, cs| 223: lines << i 224: lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 225: end 226: lines << 'end' 227: else 228: lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"}) 229: end 230: 231: lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable 232: lines << 'sql' 233: lines << 'end' 234: 235: mod.class_eval lines.join("\n"), __FILE__, __LINE__ 236: end
Append literalization of boolean constant to SQL string.
# File lib/sequel/dataset/sql.rb, line 288 288: def boolean_constant_sql_append(sql, constant) 289: if (constant == true || constant == false) && !supports_where_true? 290: sql << (constant == true ? '(1 = 1)' : '(1 = 0)') 291: else 292: literal_append(sql, constant) 293: end 294: end
Append literalization of case expression to SQL string.
# File lib/sequel/dataset/sql.rb, line 297 297: def case_expression_sql_append(sql, ce) 298: sql << '(CASE' 299: if ce.expression? 300: sql << ' ' 301: literal_append(sql, ce.expression) 302: end 303: w = " WHEN " 304: t = " THEN " 305: ce.conditions.each do |c,r| 306: sql << w 307: literal_append(sql, c) 308: sql << t 309: literal_append(sql, r) 310: end 311: sql << " ELSE " 312: literal_append(sql, ce.default) 313: sql << " END)" 314: end
Append literalization of complex expression to SQL string.
# File lib/sequel/dataset/sql.rb, line 330 330: def complex_expression_sql_append(sql, op, args) 331: case op 332: when *IS_OPERATORS 333: r = args[1] 334: if r.nil? || supports_is_true? 335: raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r] 336: sql << '(' 337: literal_append(sql, args[0]) 338: sql << ' ' << op.to_s << ' ' 339: sql << val << ')' 340: elsif op == :IS 341: complex_expression_sql_append(sql, "=""=", args) 342: else 343: complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args[0], nil)]) 344: end 345: when :IN, "NOT IN""NOT IN" 346: cols = args[0] 347: vals = args[1] 348: col_array = true if cols.is_a?(Array) 349: if vals.is_a?(Array) 350: val_array = true 351: empty_val_array = vals == [] 352: end 353: if empty_val_array 354: literal_append(sql, empty_array_value(op, cols)) 355: elsif col_array 356: if !supports_multiple_column_in? 357: if val_array 358: expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})}) 359: literal_append(sql, op == :IN ? expr : ~expr) 360: else 361: old_vals = vals 362: vals = vals.naked if vals.is_a?(Sequel::Dataset) 363: vals = vals.to_a 364: val_cols = old_vals.columns 365: complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}]) 366: end 367: else 368: # If the columns and values are both arrays, use array_sql instead of 369: # literal so that if values is an array of two element arrays, it 370: # will be treated as a value list instead of a condition specifier. 371: sql << '(' 372: literal_append(sql, cols) 373: sql << ' ' << op.to_s << ' ' 374: if val_array 375: array_sql_append(sql, vals) 376: else 377: literal_append(sql, vals) 378: end 379: sql << ')' 380: end 381: else 382: sql << '(' 383: literal_append(sql, cols) 384: sql << ' ' << op.to_s << ' ' 385: literal_append(sql, vals) 386: sql << ')' 387: end 388: when :LIKE, 'NOT LIKE''NOT LIKE' 389: sql << '(' 390: literal_append(sql, args[0]) 391: sql << ' ' << op.to_s << ' ' 392: literal_append(sql, args[1]) 393: if requires_like_escape? 394: sql << " ESCAPE " 395: literal_append(sql, "\\") 396: end 397: sql << ')' 398: when :ILIKE, 'NOT ILIKE''NOT ILIKE' 399: complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : "NOT LIKE""NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)}) 400: when :** 401: function_sql_append(sql, Sequel.function(:power, *args)) 402: when *TWO_ARITY_OPERATORS 403: if REGEXP_OPERATORS.include?(op) && !supports_regexp? 404: raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}" 405: end 406: sql << '(' 407: literal_append(sql, args[0]) 408: sql << ' ' << op.to_s << ' ' 409: literal_append(sql, args[1]) 410: sql << ')' 411: when *N_ARITY_OPERATORS 412: sql << '(' 413: c = false 414: op_str = " #{op} " 415: args.each do |a| 416: sql << op_str if c 417: literal_append(sql, a) 418: c ||= true 419: end 420: sql << ')' 421: when :NOT 422: sql << 'NOT ' 423: literal_append(sql, args[0]) 424: when :NOOP 425: literal_append(sql, args[0]) 426: when 'B~''B~' 427: sql << '~' 428: literal_append(sql, args[0]) 429: when :extract 430: sql << 'extract(' << args[0].to_s << ' FROM ' 431: literal_append(sql, args[1]) 432: sql << ')' 433: else 434: raise(InvalidOperation, "invalid operator #{op}") 435: end 436: end
Append literalization of delayed evaluation to SQL string, causing the delayed evaluation proc to be evaluated.
# File lib/sequel/dataset/sql.rb, line 445 445: def delayed_evaluation_sql_append(sql, delay) 446: # Delayed evaluations are used specifically so the SQL 447: # can differ in subsequent calls, so we definitely don't 448: # want to cache the sql in this case. 449: disable_sql_caching! 450: 451: if recorder = @opts[:placeholder_literalizer] 452: recorder.use(sql, lambda{delay.call(self)}, nil) 453: else 454: literal_append(sql, delay.call(self)) 455: end 456: end
Append literalization of function call to SQL string.
# File lib/sequel/dataset/sql.rb, line 459 459: def function_sql_append(sql, f) 460: name = f.name 461: opts = f.opts 462: 463: if opts[:emulate] 464: if emulate_function?(name) 465: emulate_function_sql_append(sql, f) 466: return 467: end 468: 469: name = native_function_name(name) 470: end 471: 472: sql << 'LATERAL ' if opts[:lateral] 473: 474: case name 475: when SQL::Identifier 476: if supports_quoted_function_names? && opts[:quoted] 477: literal_append(sql, name) 478: else 479: sql << name.value.to_s 480: end 481: when SQL::QualifiedIdentifier 482: if supports_quoted_function_names? && opts[:quoted] != false 483: literal_append(sql, name) 484: else 485: sql << split_qualifiers(name).join('.') 486: end 487: else 488: if supports_quoted_function_names? && opts[:quoted] 489: quote_identifier_append(sql, name) 490: else 491: sql << name.to_s 492: end 493: end 494: 495: sql << '(' 496: if opts[:*] 497: sql << '*' 498: else 499: sql << "DISTINCT " if opts[:distinct] 500: expression_list_append(sql, f.args) 501: if order = opts[:order] 502: sql << " ORDER BY " 503: expression_list_append(sql, order) 504: end 505: end 506: sql << ')' 507: 508: if group = opts[:within_group] 509: sql << " WITHIN GROUP (ORDER BY " 510: expression_list_append(sql, group) 511: sql << ')' 512: end 513: 514: if filter = opts[:filter] 515: sql << " FILTER (WHERE " 516: literal_append(sql, filter_expr(filter, &opts[:filter_block])) 517: sql << ')' 518: end 519: 520: if window = opts[:over] 521: sql << ' OVER ' 522: window_sql_append(sql, window.opts) 523: end 524: 525: if opts[:with_ordinality] 526: sql << " WITH ORDINALITY" 527: end 528: end
Append literalization of JOIN clause without ON or USING to SQL string.
# File lib/sequel/dataset/sql.rb, line 531 531: def join_clause_sql_append(sql, jc) 532: table = jc.table 533: table_alias = jc.table_alias 534: table_alias = nil if table == table_alias && !jc.column_aliases 535: sql << ' ' << join_type_sql(jc.join_type) << ' ' 536: identifier_append(sql, table) 537: as_sql_append(sql, table_alias, jc.column_aliases) if table_alias 538: end
Append literalization of ordered expression to SQL string.
# File lib/sequel/dataset/sql.rb, line 562 562: def ordered_expression_sql_append(sql, oe) 563: literal_append(sql, oe.expression) 564: sql << (oe.descending ? ' DESC' : ' ASC') 565: case oe.nulls 566: when :first 567: sql << " NULLS FIRST" 568: when :last 569: sql << " NULLS LAST" 570: end 571: end
Append literalization of placeholder literal string to SQL string.
# File lib/sequel/dataset/sql.rb, line 574 574: def placeholder_literal_string_sql_append(sql, pls) 575: args = pls.args 576: str = pls.str 577: sql << '(' if pls.parens 578: if args.is_a?(Hash) 579: if args.empty? 580: sql << str 581: else 582: re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/ 583: while true 584: previous, q, str = str.partition(re) 585: sql << previous 586: literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty? 587: break if str.empty? 588: end 589: end 590: elsif str.is_a?(Array) 591: len = args.length 592: str.each_with_index do |s, i| 593: sql << s 594: literal_append(sql, args[i]) unless i == len 595: end 596: unless str.length == args.length || str.length == args.length + 1 597: raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array" 598: end 599: else 600: i = -1 601: match_len = args.length - 1 602: while true 603: previous, q, str = str.partition('?') 604: sql << previous 605: literal_append(sql, args.at(i+=1)) unless q.empty? 606: if str.empty? 607: unless i == match_len 608: raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string" 609: end 610: break 611: end 612: end 613: end 614: sql << ')' if pls.parens 615: end
Append literalization of qualified identifier to SQL string. If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.
# File lib/sequel/dataset/sql.rb, line 620 620: def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) 621: identifier_append(sql, table) 622: sql << '.' 623: identifier_append(sql, column) 624: end
Append literalization of unqualified identifier to SQL string. Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.
# File lib/sequel/dataset/sql.rb, line 630 630: def quote_identifier_append(sql, name) 631: if name.is_a?(LiteralString) 632: sql << name 633: else 634: name = name.value if name.is_a?(SQL::Identifier) 635: name = input_identifier(name) 636: if quote_identifiers? 637: quoted_identifier_append(sql, name) 638: else 639: sql << name 640: end 641: end 642: end
Append literalization of identifier or unqualified identifier to SQL string.
# File lib/sequel/dataset/sql.rb, line 645 645: def quote_schema_table_append(sql, table) 646: schema, table = schema_and_table(table) 647: if schema 648: quote_identifier_append(sql, schema) 649: sql << '.' 650: end 651: quote_identifier_append(sql, table) 652: end
Append literalization of quoted identifier to SQL string. This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).
# File lib/sequel/dataset/sql.rb, line 658 658: def quoted_identifier_append(sql, name) 659: sql << '"' << name.to_s.gsub('"', '""') << '"' 660: end
Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.
Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).
# File lib/sequel/dataset/sql.rb, line 669 669: def schema_and_table(table_name, sch=nil) 670: sch = sch.to_s if sch 671: case table_name 672: when Symbol 673: s, t, _ = split_symbol(table_name) 674: [s||sch, t] 675: when SQL::QualifiedIdentifier 676: [table_name.table.to_s, table_name.column.to_s] 677: when SQL::Identifier 678: [sch, table_name.value.to_s] 679: when String 680: [sch, table_name] 681: else 682: raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String' 683: end 684: end
Splits table_name into an array of strings.
ds.split_qualifiers(:s) # ['s'] ds.split_qualifiers(Sequel[:t][:s]) # ['t', 's'] ds.split_qualifiers(Sequel[:d][:t][:s]) # ['d', 't', 's'] ds.split_qualifiers(Sequel.qualify(Sequel[:h][:d], Sequel[:t][:s])) # ['h', 'd', 't', 's']
# File lib/sequel/dataset/sql.rb, line 692 692: def split_qualifiers(table_name, *args) 693: case table_name 694: when SQL::QualifiedIdentifier 695: split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil) 696: else 697: sch, table = schema_and_table(table_name, *args) 698: sch ? [sch, table] : [table] 699: end 700: end
Append literalization of subscripts (SQL array accesses) to SQL string.
# File lib/sequel/dataset/sql.rb, line 703 703: def subscript_sql_append(sql, s) 704: literal_append(sql, s.expression) 705: sql << '[' 706: sub = s.sub 707: if sub.length == 1 && (range = sub.first).is_a?(Range) 708: literal_append(sql, range.begin) 709: sql << ':' 710: e = range.end 711: e -= 1 if range.exclude_end? && e.is_a?(Integer) 712: literal_append(sql, e) 713: else 714: expression_list_append(sql, s.sub) 715: end 716: sql << ']' 717: end
Append literalization of windows (for window functions) to SQL string.
# File lib/sequel/dataset/sql.rb, line 720 720: def window_sql_append(sql, opts) 721: raise(Error, 'This dataset does not support window functions') unless supports_window_functions? 722: sql << '(' 723: window, part, order, frame = opts.values_at(:window, :partition, :order, :frame) 724: space = false 725: space_s = ' ' 726: if window 727: literal_append(sql, window) 728: space = true 729: end 730: if part 731: sql << space_s if space 732: sql << "PARTITION BY " 733: expression_list_append(sql, Array(part)) 734: space = true 735: end 736: if order 737: sql << space_s if space 738: sql << "ORDER BY " 739: expression_list_append(sql, Array(order)) 740: space = true 741: end 742: case frame 743: when nil 744: # nothing 745: when :all 746: sql << space_s if space 747: sql << "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING" 748: when :rows 749: sql << space_s if space 750: sql << "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW" 751: when String 752: sql << space_s if space 753: sql << frame 754: else 755: raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil" 756: end 757: sql << ')' 758: end
Dataset graphing automatically creates unique aliases columns in join tables that overlap with already selected column aliases. All of these methods return modified copies of the receiver.
Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_append when graphing). See set_graph_aliases.
DB[:table].add_graph_aliases(some_alias: [:table, :column]) # SELECT ..., table.column AS some_alias
# File lib/sequel/dataset/graph.rb, line 18 18: def add_graph_aliases(graph_aliases) 19: graph = opts[:graph] 20: unless (graph && (ga = graph[:column_aliases])) 21: raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases" 22: end 23: columns, graph_aliases = graph_alias_columns(graph_aliases) 24: select_append(*columns).clone(:graph => Hash[graph].merge!(:column_aliases=>Hash[ga].merge!(graph_aliases).freeze).freeze) 25: end
Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.
Arguments:
dataset : | Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression. |
join_conditions : | Any condition(s) allowed by join_table. |
block : | A block that is passed to join_table. |
Options:
:from_self_alias : | The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use. |
:implicit_qualifier : | The qualifier of implicit conditions, see join_table. |
:join_only : | Only join the tables, do not change the selected columns. |
:join_type : | The type of join to use (passed to join_table). Defaults to :left_outer. |
:qualify: | The type of qualification to do, see join_table. |
:select : | An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table. |
:table_alias : | The alias to use for the table. If not specified, doesn‘t alias the table. You will get an error if the alias (or table) name is used more than once. |
# File lib/sequel/dataset/graph.rb, line 53 53: def graph(dataset, join_conditions = nil, options = OPTS, &block) 54: # Allow the use of a dataset or symbol as the first argument 55: # Find the table name/dataset based on the argument 56: table_alias = options[:table_alias] 57: table = dataset 58: create_dataset = true 59: 60: case dataset 61: when Symbol 62: # let alias be the same as the table name (sans any optional schema) 63: # unless alias explicitly given in the symbol using ___ notation and symbol splitting is enabled 64: table_alias ||= split_symbol(table).compact.last 65: when Dataset 66: if dataset.simple_select_all? 67: table = dataset.opts[:from].first 68: table_alias ||= table 69: else 70: table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1) 71: end 72: create_dataset = false 73: when SQL::Identifier 74: table_alias ||= table.value 75: when SQL::QualifiedIdentifier 76: table_alias ||= split_qualifiers(table).last 77: when SQL::AliasedExpression 78: return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge!(options), &block) 79: else 80: raise Error, "The dataset argument should be a symbol or dataset" 81: end 82: table_alias = table_alias.to_sym 83: 84: if create_dataset 85: dataset = db.from(table) 86: end 87: 88: # Raise Sequel::Error with explanation that the table alias has been used 89: raise_alias_error = lambda do 90: raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \ 91: "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 92: end 93: 94: # Only allow table aliases that haven't been used 95: raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias) 96: 97: table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table) 98: implicit_qualifier = options[:implicit_qualifier] 99: ds = self 100: 101: # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs) 102: if (@opts[:graph_from_self] != false && !@opts[:graph] && joined_dataset?) 103: from_selfed = true 104: implicit_qualifier = options[:from_self_alias] || first_source 105: ds = ds.from_self(:alias=>implicit_qualifier) 106: end 107: 108: # Join the table early in order to avoid cloning the dataset twice 109: ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &block) 110: 111: return ds if options[:join_only] 112: 113: opts = ds.opts 114: 115: # Whether to include the table in the result set 116: add_table = options[:select] == false ? false : true 117: 118: if graph = opts[:graph] 119: graph = graph.dup 120: select = opts[:select].dup 121: [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup} 122: else 123: # Setup the initial graph data structure if it doesn't exist 124: qualifier = ds.first_source_alias 125: master = alias_symbol(qualifier) 126: raise_alias_error.call if master == table_alias 127: 128: # Master hash storing all .graph related information 129: graph = {} 130: 131: # Associates column aliases back to tables and columns 132: column_aliases = graph[:column_aliases] = {} 133: 134: # Associates table alias (the master is never aliased) 135: table_aliases = graph[:table_aliases] = {master=>self} 136: 137: # Keep track of the alias numbers used 138: ca_num = graph[:column_alias_num] = Hash.new(0) 139: 140: # All columns in the master table are never 141: # aliased, but are not included if set_graph_aliases 142: # has been used. 143: if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll))) 144: select = select.map do |sel| 145: raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" unless column = _hash_key_symbol(sel) 146: column_aliases[column] = [master, column] 147: if from_selfed 148: # Initial dataset was wrapped in subselect, selected all 149: # columns in the subselect, qualified by the subselect alias. 150: Sequel.qualify(qualifier, Sequel.identifier(column)) 151: else 152: # Initial dataset not wrapped in subslect, just make 153: # sure columns are qualified in some way. 154: qualified_expression(sel, qualifier) 155: end 156: end 157: else 158: select = columns.map do |column| 159: column_aliases[column] = [master, column] 160: SQL::QualifiedIdentifier.new(qualifier, column) 161: end 162: end 163: end 164: 165: # Add the table alias to the list of aliases 166: # Even if it isn't been used in the result set, 167: # we add a key for it with a nil value so we can check if it 168: # is used more than once 169: table_aliases = graph[:table_aliases] 170: table_aliases[table_alias] = add_table ? dataset : nil 171: 172: # Add the columns to the selection unless we are ignoring them 173: if add_table 174: column_aliases = graph[:column_aliases] 175: ca_num = graph[:column_alias_num] 176: # Which columns to add to the result set 177: cols = options[:select] || dataset.columns 178: # If the column hasn't been used yet, don't alias it. 179: # If it has been used, try table_column. 180: # If that has been used, try table_column_N 181: # using the next value of N that we know hasn't been 182: # used 183: cols.each do |column| 184: col_alias, identifier = if column_aliases[column] 185: column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}" 186: if column_aliases[column_alias] 187: column_alias_num = ca_num[column_alias] 188: column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}" 189: ca_num[column_alias] += 1 190: end 191: [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)] 192: else 193: ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column) 194: [column, ident] 195: end 196: column_aliases[col_alias] = [table_alias, column].freeze 197: select.push(identifier) 198: end 199: end 200: [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze} 201: ds = ds.clone(:graph=>graph.freeze) 202: ds.select(*select) 203: end
This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.
graph_aliases should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.
DB[:artists].graph(:albums, :artist_id: :id). set_graph_aliases(name: :artists, album_name: [:albums, :name], forty_two: [:albums, :fourtwo, 42]).first # SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
# File lib/sequel/dataset/graph.rb, line 228 228: def set_graph_aliases(graph_aliases) 229: columns, graph_aliases = graph_alias_columns(graph_aliases) 230: if graph = opts[:graph] 231: select(*columns).clone(:graph => Hash[graph].merge!(:column_aliases=>graph_aliases.freeze).freeze) 232: else 233: raise Error, "cannot call #set_graph_aliases on an ungraphed dataset" 234: end 235: end
These methods all return modified copies of the receiver.
EXTENSIONS | = | {} | Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension). | |
EMPTY_ARRAY | = | [].freeze | ||
COLUMN_CHANGE_OPTS | = | [:select, :sql, :from, :join].freeze | The dataset options that require the removal of cached columns if changed. | |
NON_SQL_OPTIONS | = | [:server, :graph, :row_proc, :quote_identifiers, :skip_symbol_cache].freeze | Which options don‘t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table. | |
CONDITIONED_JOIN_TYPES | = | [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left].freeze | These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call. | |
UNCONDITIONED_JOIN_TYPES | = | [:natural, :natural_left, :natural_right, :natural_full, :cross].freeze | These symbols have _join methods created (e.g. natural_join). They accept a table argument and options hash which is passed to join_table, and they raise an error if called with a block. | |
JOIN_METHODS | = | ((CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]).freeze | All methods that return modified datasets with a joined table added. | |
QUERY_METHODS | = | ((<<-METHS).split.map(&:to_sym) + JOIN_METHODS).freeze add_graph_aliases distinct except exclude exclude_having filter for_update from from_self graph grep group group_and_count group_append group_by having intersect invert limit lock_style naked offset or order order_append order_by order_more order_prepend qualify reverse reverse_order select select_all select_append select_group select_more server set_graph_aliases unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS ).split.map(&:to_sym) + JOIN_METHODS).freeze | Methods that return modified datasets | |
SIMPLE_SELECT_ALL_ALLOWED_FROM | = | [Symbol, SQL::Identifier, SQL::QualifiedIdentifier].freeze | From types allowed to be considered a simple_select_all |
Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.
If mod is a module, this also registers a Database extension that will extend all of the database‘s datasets.
# File lib/sequel/dataset/query.rb, line 56 56: def self.register_extension(ext, mod=nil, &block) 57: if mod 58: raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block 59: if mod.is_a?(Module) 60: block = proc{|ds| ds.extend(mod)} 61: Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)} 62: else 63: block = mod 64: end 65: end 66: Sequel.synchronize{EXTENSIONS[ext] = block} 67: end
Returns a new clone of the dataset with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.
# File lib/sequel/dataset/query.rb, line 85 85: def clone(opts = (return self; nil)) 86: c = super(:freeze=>false) 87: c.opts.merge!(opts) 88: unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)} 89: c.clear_columns_cache 90: end 91: c.freeze 92: end
Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. If a block is given, it is treated as a virtual row block, similar to where. Raises an error if arguments are given and DISTINCT ON is not supported.
DB[:items].distinct # SQL: SELECT DISTINCT * FROM items DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id DB[:items].order(:id).distinct{func(:id)} # SQL: SELECT DISTINCT ON (func(id)) * FROM items ORDER BY id
There is support for emualting the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn‘t work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.
# File lib/sequel/dataset/query.rb, line 122 122: def distinct(*args, &block) 123: virtual_row_columns(args, block) 124: if args.empty? 125: cached_dataset(:_distinct_ds){clone(:distinct => EMPTY_ARRAY)} 126: else 127: raise(InvalidOperation, "DISTINCT ON not supported") unless supports_distinct_on? 128: clone(:distinct => args.freeze) 129: end 130: end
Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
:alias : | Use the given value as the from_self alias |
:all : | Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur |
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].except(DB[:other_items]) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1 DB[:items].except(DB[:other_items], all: true, from_self: false) # SELECT * FROM items EXCEPT ALL SELECT * FROM other_items DB[:items].except(DB[:other_items], alias: :i) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 149 149: def except(dataset, opts=OPTS) 150: raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except? 151: raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all? 152: compound_clone(:except, dataset, opts) 153: end
Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.
DB[:items].exclude(category: 'software') # SELECT * FROM items WHERE (category != 'software') DB[:items].exclude(category: 'software', id: 3) # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
Also note that SQL uses 3-valued boolean logic (true, false, NULL), so the inverse of a true condition is a false condition, and will still not match rows that were NULL originally. If you take the earlier example:
DB[:items].exclude(category: 'software') # SELECT * FROM items WHERE (category != 'software')
Note that this does not match rows where category is NULL. This is because NULL is an unknown value, and you do not know whether or not the NULL category is software. You can explicitly specify how to handle NULL values if you want:
DB[:items].exclude(Sequel.~(category: nil) & {category: 'software'}) # SELECT * FROM items WHERE ((category IS NULL) OR (category != 'software'))
# File lib/sequel/dataset/query.rb, line 179 179: def exclude(*cond, &block) 180: add_filter(:where, cond, true, &block) 181: end
Inverts the given conditions and adds them to the HAVING clause.
DB[:items].select_group(:name).exclude_having{count(name) < 2} # SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)
See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.
# File lib/sequel/dataset/query.rb, line 190 190: def exclude_having(*cond, &block) 191: add_filter(:having, cond, true, &block) 192: end
Return a clone of the dataset loaded with the given dataset extensions. If no related extension file exists or the extension does not have specific support for Dataset objects, an Error will be raised.
# File lib/sequel/dataset/query.rb, line 198 198: def extension(*a) 199: c = _clone(:freeze=>false) 200: c.send(:_extension!, a) 201: c.freeze 202: end
Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where.
DB[:items].from # SQL: SELECT * DB[:items].from(:blah) # SQL: SELECT * FROM blah DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
# File lib/sequel/dataset/query.rb, line 234 234: def from(*source, &block) 235: virtual_row_columns(source, block) 236: table_alias_num = 0 237: ctes = nil 238: source.map! do |s| 239: case s 240: when Dataset 241: if hoist_cte?(s) 242: ctes ||= [] 243: ctes += s.opts[:with] 244: s = s.clone(:with=>nil) 245: end 246: SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1)) 247: when Symbol 248: sch, table, aliaz = split_symbol(s) 249: if aliaz 250: s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table) 251: SQL::AliasedExpression.new(s, aliaz.to_sym) 252: else 253: s 254: end 255: else 256: s 257: end 258: end 259: o = {:from=>source.empty? ? nil : source.freeze} 260: o[:with] = ((opts[:with] || EMPTY_ARRAY) + ctes).freeze if ctes 261: o[:num_dataset_sources] = table_alias_num if table_alias_num > 0 262: clone(o) 263: end
Returns a dataset selecting from the current dataset. Options:
:alias : | Controls the alias of the table |
:column_aliases : | Also aliases columns, using derived column lists. Only used in conjunction with :alias. |
ds = DB[:items].order(:name).select(:id, :name) # SELECT id,name FROM items ORDER BY name ds.from_self # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1 ds.from_self(alias: :foo) # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo ds.from_self(alias: :foo, column_aliases: [:c1, :c2]) # SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)
# File lib/sequel/dataset/query.rb, line 282 282: def from_self(opts=OPTS) 283: fs = {} 284: @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)} 285: pr = proc do 286: c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self) 287: if cols = _columns 288: c.send(:columns=, cols) 289: end 290: c 291: end 292: 293: cache ? cached_dataset(:_from_self_ds, &pr) : pr.call 294: end
Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions if the database supports that. Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.
Options (all are boolean):
:all_columns : | All columns must be matched to any of the given patterns. |
:all_patterns : | All patterns must match at least one of the columns. |
:case_insensitive : | Use a case insensitive pattern match (the default is case sensitive if the database supports it). |
If both :all_columns and :all_patterns are true, all columns must match all patterns.
Examples:
dataset.grep(:a, '%test%') # SELECT * FROM items WHERE (a LIKE '%test%' ESCAPE '\') dataset.grep([:a, :b], %w'%test% foo') # SELECT * FROM items WHERE ((a LIKE '%test%' ESCAPE '\') OR (a LIKE 'foo' ESCAPE '\') # OR (b LIKE '%test%' ESCAPE '\') OR (b LIKE 'foo' ESCAPE '\')) dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true) # SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (b LIKE '%foo%' ESCAPE '\')) # AND ((a LIKE '%bar%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\'))) dataset.grep([:a, :b], %w'%foo% %bar%', all_columns: true) # SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (a LIKE '%bar%' ESCAPE '\')) # AND ((b LIKE '%foo%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\'))) dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true, all_columns: true) # SELECT * FROM a WHERE ((a LIKE '%foo%' ESCAPE '\') AND (b LIKE '%foo%' ESCAPE '\') # AND (a LIKE '%bar%' ESCAPE '\') AND (b LIKE '%bar%' ESCAPE '\'))
# File lib/sequel/dataset/query.rb, line 331 331: def grep(columns, patterns, opts=OPTS) 332: if opts[:all_patterns] 333: conds = Array(patterns).map do |pat| 334: SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)}) 335: end 336: where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds)) 337: else 338: conds = Array(columns).map do |c| 339: SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)}) 340: end 341: where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds)) 342: end 343: end
Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where.
DB[:items].group(:id) # SELECT * FROM items GROUP BY id DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
# File lib/sequel/dataset/query.rb, line 352 352: def group(*columns, &block) 353: virtual_row_columns(columns, block) 354: clone(:group => (columns.compact.empty? ? nil : columns.freeze)) 355: end
Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where.
Examples:
DB[:items].group_and_count(:name).all # SELECT name, count(*) AS count FROM items GROUP BY name # => [{:name=>'a', :count=>1}, ...] DB[:items].group_and_count(:first_name, :last_name).all # SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name # => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...] DB[:items].group_and_count(Sequel[:first_name].as(:name)).all # SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name # => [{:name=>'a', :count=>1}, ...] DB[:items].group_and_count{substr(:first_name, 1, 1).as(:initial)}.all # SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1) # => [{:initial=>'a', :count=>1}, ...]
# File lib/sequel/dataset/query.rb, line 383 383: def group_and_count(*columns, &block) 384: select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT) 385: end
Returns a copy of the dataset with the given columns added to the list of existing columns to group on. If no existing columns are present this method simply sets the columns as the initial ones to group on.
DB[:items].group_append(:b) # SELECT * FROM items GROUP BY b DB[:items].group(:a).group_append(:b) # SELECT * FROM items GROUP BY a, b
# File lib/sequel/dataset/query.rb, line 393 393: def group_append(*columns, &block) 394: columns = @opts[:group] + columns if @opts[:group] 395: group(*columns, &block) 396: end
Adds the appropriate CUBE syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 399 399: def group_cube 400: raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube? 401: clone(:group_options=>:cube) 402: end
Adds the appropriate ROLLUP syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 405 405: def group_rollup 406: raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup? 407: clone(:group_options=>:rollup) 408: end
Adds the appropriate GROUPING SETS syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 411 411: def grouping_sets 412: raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets? 413: clone(:group_options=>"grouping sets""grouping sets") 414: end
Returns a copy of the dataset with the HAVING conditions changed. See where for argument types.
DB[:items].group(:sum).having(sum: 10) # SELECT * FROM items GROUP BY sum HAVING (sum = 10)
# File lib/sequel/dataset/query.rb, line 420 420: def having(*cond, &block) 421: add_filter(:having, cond, &block) 422: end
Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
:alias : | Use the given value as the from_self alias |
:all : | Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur |
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].intersect(DB[:other_items]) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1 DB[:items].intersect(DB[:other_items], all: true, from_self: false) # SELECT * FROM items INTERSECT ALL SELECT * FROM other_items DB[:items].intersect(DB[:other_items], alias: :i) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 441 441: def intersect(dataset, opts=OPTS) 442: raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except? 443: raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all? 444: compound_clone(:intersect, dataset, opts) 445: end
Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.
DB[:items].where(category: 'software').invert # SELECT * FROM items WHERE (category != 'software') DB[:items].where(category: 'software', id: 3).invert # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.
# File lib/sequel/dataset/query.rb, line 458 458: def invert 459: cached_dataset(:_invert_ds) do 460: having, where = @opts.values_at(:having, :where) 461: if having.nil? && where.nil? 462: where(false) 463: else 464: o = {} 465: o[:having] = SQL::BooleanExpression.invert(having) if having 466: o[:where] = SQL::BooleanExpression.invert(where) if where 467: clone(o) 468: end 469: end 470: end
Alias of inner_join
# File lib/sequel/dataset/query.rb, line 473 473: def join(*args, &block) 474: inner_join(*args, &block) 475: end
Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.
Takes the following arguments:
type : | The type of join to do (e.g. :inner) | ||||||||
table : | table to join into the current dataset.
Generally one of the following types:
| ||||||||
expr : | conditions used when joining, depends on type:
| ||||||||
options : | a hash of options, with the following keys supported:
| ||||||||
block : | The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike where, this block is not treated as a virtual row block. |
Examples:
DB[:a].join_table(:cross, :b) # SELECT * FROM a CROSS JOIN b DB[:a].join_table(:inner, DB[:b], c: d) # SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d) DB[:a].join_table(:left, Sequel[:b].as(:c), [:d]) # SELECT * FROM a LEFT JOIN b AS c USING (d) DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js| (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)} end # SELECT * FROM a NATURAL JOIN b INNER JOIN c # ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
# File lib/sequel/dataset/query.rb, line 536 536: def join_table(type, table, expr=nil, options=OPTS, &block) 537: if hoist_cte?(table) 538: s, ds = hoist_cte(table) 539: return s.join_table(type, ds, expr, options, &block) 540: end 541: 542: using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)} 543: if using_join && !supports_join_using? 544: h = {} 545: expr.each{|e| h[e] = e} 546: return join_table(type, table, h, options) 547: end 548: 549: table_alias = options[:table_alias] 550: 551: if table.is_a?(SQL::AliasedExpression) 552: table_expr = if table_alias 553: SQL::AliasedExpression.new(table.expression, table_alias, table.columns) 554: else 555: table 556: end 557: table = table_expr.expression 558: table_name = table_alias = table_expr.alias 559: elsif table.is_a?(Dataset) 560: if table_alias.nil? 561: table_alias_num = (@opts[:num_dataset_sources] || 0) + 1 562: table_alias = dataset_alias(table_alias_num) 563: end 564: table_name = table_alias 565: table_expr = SQL::AliasedExpression.new(table, table_alias) 566: else 567: table, implicit_table_alias = split_alias(table) 568: table_alias ||= implicit_table_alias 569: table_name = table_alias || table 570: table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table 571: end 572: 573: join = if expr.nil? and !block 574: SQL::JoinClause.new(type, table_expr) 575: elsif using_join 576: raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block 577: SQL::JoinUsingClause.new(expr, type, table_expr) 578: else 579: last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias 580: qualify_type = options[:qualify] 581: if Sequel.condition_specifier?(expr) 582: expr = expr.map do |k, v| 583: qualify_type = default_join_table_qualification if qualify_type.nil? 584: case qualify_type 585: when false 586: nil # Do no qualification 587: when :deep 588: k = Sequel::Qualifier.new(table_name).transform(k) 589: v = Sequel::Qualifier.new(last_alias).transform(v) 590: else 591: k = qualified_column_name(k, table_name) if k.is_a?(Symbol) 592: v = qualified_column_name(v, last_alias) if v.is_a?(Symbol) 593: end 594: [k,v] 595: end 596: expr = SQL::BooleanExpression.from_value_pairs(expr) 597: end 598: if block 599: expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY) 600: expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2 601: end 602: SQL::JoinOnClause.new(expr, type, table_expr) 603: end 604: 605: opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze} 606: opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false 607: opts[:num_dataset_sources] = table_alias_num if table_alias_num 608: clone(opts) 609: end
Marks this dataset as a lateral dataset. If used in another dataset‘s FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:
DB.from(:a, DB[:b].where(Sequel[:a][:c]=>Sequel[:b][:d]).lateral) # SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
# File lib/sequel/dataset/query.rb, line 631 631: def lateral 632: cached_dataset(:_lateral_ds){clone(:lateral=>true)} 633: end
If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.
DB[:items].limit(10) # SELECT * FROM items LIMIT 10 DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20 DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10 DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10 DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
# File lib/sequel/dataset/query.rb, line 645 645: def limit(l, o = (no_offset = true; nil)) 646: return from_self.limit(l, o) if @opts[:sql] 647: 648: if l.is_a?(Range) 649: no_offset = false 650: o = l.first 651: l = l.last - l.first + (l.exclude_end? ? 0 : 1) 652: end 653: l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString) 654: if l.is_a?(Integer) 655: raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1 656: end 657: 658: ds = clone(:limit=>l) 659: ds = ds.offset(o) unless no_offset 660: ds 661: end
Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.
A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).
DB[:items].lock_style('FOR SHARE NOWAIT') # SELECT * FROM items FOR SHARE NOWAIT DB[:items].lock_style('FOR UPDATE OF table1 SKIP LOCKED') # SELECT * FROM items FOR UPDATE OF table1 SKIP LOCKED
# File lib/sequel/dataset/query.rb, line 675 675: def lock_style(style) 676: clone(:lock => style) 677: end
Returns a copy of the dataset that will raise a DatabaseLockTimeout instead of waiting for rows that are locked by another transaction
DB[:items].for_update.nowait # SELECT * FROM items FOR UPDATE NOWAIT
# File lib/sequel/dataset/query.rb, line 693 693: def nowait 694: cached_dataset(:_nowait_ds) do 695: raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait? 696: clone(:nowait=>true) 697: end 698: end
Returns a copy of the dataset with a specified order. Can be safely combined with limit. If you call limit with an offset, it will override override the offset if you‘ve called offset first.
DB[:items].offset(10) # SELECT * FROM items OFFSET 10
# File lib/sequel/dataset/query.rb, line 705 705: def offset(o) 706: o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString) 707: if o.is_a?(Integer) 708: raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0 709: end 710: clone(:offset => o) 711: end
Adds an alternate filter to an existing WHERE clause using OR. If there is no WHERE clause, then the default is WHERE true, and OR would be redundant, so return the dataset in that case.
DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b DB[:items].or(:b) # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 719 719: def or(*cond, &block) 720: if @opts[:where].nil? 721: self 722: else 723: add_filter(:where, cond, false, :OR, &block) 724: end 725: end
Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where.
DB[:items].order(:name) # SELECT * FROM items ORDER BY name DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b DB[:items].order(Sequel[:a] + :b) # SELECT * FROM items ORDER BY (a + b) DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC DB[:items].order(nil) # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 741 741: def order(*columns, &block) 742: virtual_row_columns(columns, block) 743: clone(:order => (columns.compact.empty?) ? nil : columns.freeze) 744: end
Returns a copy of the dataset with the order columns added to the end of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b DB[:items].order(:a).order_append(:b) # SELECT * FROM items ORDER BY a, b
# File lib/sequel/dataset/query.rb, line 751 751: def order_append(*columns, &block) 752: columns = @opts[:order] + columns if @opts[:order] 753: order(*columns, &block) 754: end
Alias of order_append.
# File lib/sequel/dataset/query.rb, line 762 762: def order_more(*columns, &block) 763: order_append(*columns, &block) 764: end
Returns a copy of the dataset with the order columns added to the beginning of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
# File lib/sequel/dataset/query.rb, line 771 771: def order_prepend(*columns, &block) 772: ds = order(*columns, &block) 773: @opts[:order] ? ds.order_append(*@opts[:order]) : ds 774: end
Qualify to the given table, or first source if no table is given.
DB[:items].where(id: 1).qualify # SELECT items.* FROM items WHERE (items.id = 1) DB[:items].where(id: 1).qualify(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 783 783: def qualify(table=(cache=true; first_source)) 784: o = @opts 785: return self if o[:sql] 786: 787: pr = proc do 788: h = {} 789: (o.keys & QUALIFY_KEYS).each do |k| 790: h[k] = qualified_expression(o[k], table) 791: end 792: h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty? 793: clone(h) 794: end 795: 796: cache ? cached_dataset(:_qualify_ds, &pr) : pr.call 797: end
Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.
DB[:items].returning # RETURNING * DB[:items].returning(nil) # RETURNING NULL DB[:items].returning(:id, :name) # RETURNING id, name DB[:items].returning.insert(:a=>1) do |hash| # hash for each row inserted, with values for all columns end DB[:items].returning.update(:a=>1) do |hash| # hash for each row updated, with values for all columns end DB[:items].returning.delete(:a=>1) do |hash| # hash for each row deleted, with values for all columns end
# File lib/sequel/dataset/query.rb, line 817 817: def returning(*values) 818: if values.empty? 819: cached_dataset(:_returning_ds) do 820: raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert) 821: clone(:returning=>EMPTY_ARRAY) 822: end 823: else 824: raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert) 825: clone(:returning=>values.freeze) 826: end 827: end
Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.
DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
# File lib/sequel/dataset/query.rb, line 836 836: def reverse(*order, &block) 837: if order.empty? && !block 838: cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))} 839: else 840: virtual_row_columns(order, block) 841: order(*invert_order(order.empty? ? @opts[:order] : order.freeze)) 842: end 843: end
Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where.
DB[:items].select(:a) # SELECT a FROM items DB[:items].select(:a, :b) # SELECT a, b FROM items DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
# File lib/sequel/dataset/query.rb, line 857 857: def select(*columns, &block) 858: virtual_row_columns(columns, block) 859: clone(:select => columns.freeze) 860: end
Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.
DB[:items].select(:a).select_all # SELECT * FROM items DB[:items].select_all(:items) # SELECT items.* FROM items DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
# File lib/sequel/dataset/query.rb, line 869 869: def select_all(*tables) 870: if tables.empty? 871: cached_dataset(:_select_all_ds){clone(:select => nil)} 872: else 873: select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze) 874: end 875: end
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.
DB[:items].select(:a).select(:b) # SELECT b FROM items DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items DB[:items].select_append(:b) # SELECT *, b FROM items
# File lib/sequel/dataset/query.rb, line 884 884: def select_append(*columns, &block) 885: cur_sel = @opts[:select] 886: if !cur_sel || cur_sel.empty? 887: unless supports_select_all_and_column? 888: return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block) 889: end 890: cur_sel = [WILDCARD] 891: end 892: select(*(cur_sel + columns), &block) 893: end
Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where.
DB[:items].select_group(:a, :b) # SELECT a, b FROM items GROUP BY a, b DB[:items].select_group(Sequel[:c].as(:a)){f(c2)} # SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
# File lib/sequel/dataset/query.rb, line 904 904: def select_group(*columns, &block) 905: virtual_row_columns(columns, block) 906: select(*columns).group(*columns.map{|c| unaliased_identifier(c)}) 907: end
Alias for select_append.
# File lib/sequel/dataset/query.rb, line 910 910: def select_more(*columns, &block) 911: select_append(*columns, &block) 912: end
Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.
DB[:items].all # Uses the :read_only or :default server DB[:items].delete # Uses the :default server DB[:items].server(:blah).delete # Uses the :blah server
# File lib/sequel/dataset/query.rb, line 923 923: def server(servr) 924: clone(:server=>servr) 925: end
If the database uses sharding and the current dataset has not had a server set, return a cloned dataset that uses the given server. Otherwise, return the receiver directly instead of returning a clone.
# File lib/sequel/dataset/query.rb, line 930 930: def server?(server) 931: if db.sharded? && !opts[:server] 932: server(server) 933: else 934: self 935: end 936: end
Specify that the check for limits/offsets when updating/deleting be skipped for the dataset.
# File lib/sequel/dataset/query.rb, line 939 939: def skip_limit_check 940: cached_dataset(:_skip_limit_check_ds) do 941: clone(:skip_limit_check=>true) 942: end 943: end
Skip locked rows when returning results from this dataset.
# File lib/sequel/dataset/query.rb, line 946 946: def skip_locked 947: cached_dataset(:_skip_locked_ds) do 948: raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked? 949: clone(:skip_locked=>true) 950: end 951: end
Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.
DB[:items].group(:a).having(a: 1).where(:b).unfiltered # SELECT * FROM items GROUP BY a
# File lib/sequel/dataset/query.rb, line 957 957: def unfiltered 958: cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)} 959: end
Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.
DB[:items].group(:a).having(a: 1).where(:b).ungrouped # SELECT * FROM items WHERE b
# File lib/sequel/dataset/query.rb, line 965 965: def ungrouped 966: cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)} 967: end
Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:
:alias : | Use the given value as the from_self alias |
:all : | Set to true to use UNION ALL instead of UNION, so duplicate rows can occur |
:from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].union(DB[:other_items]) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1 DB[:items].union(DB[:other_items], all: true, from_self: false) # SELECT * FROM items UNION ALL SELECT * FROM other_items DB[:items].union(DB[:other_items], alias: :i) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 985 985: def union(dataset, opts=OPTS) 986: compound_clone(:union, dataset, opts) 987: end
Returns a copy of the dataset with the given WHERE conditions imposed upon it.
Accepts the following argument types:
Hash, Array of pairs : | list of equality/inclusion expressions |
Symbol : | taken as a boolean column argument (e.g. WHERE active) |
Sequel::SQL::BooleanExpression, Sequel::LiteralString : | an existing condition expression, probably created using the Sequel expression filter DSL. |
where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the "Virtual Rows" guide
If both a block and regular argument are provided, they get ANDed together.
Examples:
DB[:items].where(id: 3) # SELECT * FROM items WHERE (id = 3) DB[:items].where(Sequel.lit('price < ?', 100)) # SELECT * FROM items WHERE price < 100 DB[:items].where([[:id, [1,2,3]], [:id, 0..10]]) # SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10))) DB[:items].where(Sequel.lit('price < 100')) # SELECT * FROM items WHERE price < 100 DB[:items].where(:active) # SELECT * FROM items WHERE :active DB[:items].where{price < 100} # SELECT * FROM items WHERE (price < 100)
Multiple where calls can be chained for scoping:
software = dataset.where(category: 'software').where{price < 100} # SELECT * FROM items WHERE ((category = 'software') AND (price < 100))
See the "Dataset Filtering" guide for more examples and details.
# File lib/sequel/dataset/query.rb, line 1045 1045: def where(*cond, &block) 1046: add_filter(:where, cond, &block) 1047: end
Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query. Options:
:args : | Specify the arguments/columns for the CTE, should be an array of symbols. |
:recursive : | Specify that this is a recursive CTE |
DB[:items].with(:items, DB[:syx].where(Sequel[:name].like('A%'))) # WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 1057 1057: def with(name, dataset, opts=OPTS) 1058: raise(Error, 'This dataset does not support common table expressions') unless supports_cte? 1059: if hoist_cte?(dataset) 1060: s, ds = hoist_cte(dataset) 1061: s.with(name, ds, opts) 1062: else 1063: clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze) 1064: end 1065: end
Return a clone of the dataset extended with the given modules. Note that like Object#extend, when multiple modules are provided as arguments the cloned dataset is extended with the modules in reverse order. If a block is provided, a DatasetModule is created using the block and the clone is extended with that module after any modules given as arguments.
# File lib/sequel/dataset/query.rb, line 1102 1102: def with_extend(*mods, &block) 1103: c = _clone(:freeze=>false) 1104: c.extend(*mods) unless mods.empty? 1105: c.extend(DatasetModule.new(&block)) if block 1106: c.freeze 1107: end
Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE. Options:
:args : | Specify the arguments/columns for the CTE, should be an array of symbols. |
:union_all : | Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts. |
DB[:t].with_recursive(:t, DB[:i1].select(:id, :parent_id).where(parent_id: nil), DB[:i1].join(:t, id: :parent_id).select(Sequel[:i1][:id], Sequel[:i1][:parent_id]), :args=>[:id, :parent_id]) # WITH RECURSIVE t(id, parent_id) AS ( # SELECT id, parent_id FROM i1 WHERE (parent_id IS NULL) # UNION ALL # SELECT i1.id, i1.parent_id FROM i1 INNER JOIN t ON (t.id = i1.parent_id) # ) SELECT * FROM t
# File lib/sequel/dataset/query.rb, line 1083 1083: def with_recursive(name, nonrecursive, recursive, opts=OPTS) 1084: raise(Error, 'This datatset does not support common table expressions') unless supports_cte? 1085: if hoist_cte?(nonrecursive) 1086: s, ds = hoist_cte(nonrecursive) 1087: s.with_recursive(name, ds, recursive, opts) 1088: elsif hoist_cte?(recursive) 1089: s, ds = hoist_cte(recursive) 1090: s.with_recursive(name, nonrecursive, ds, opts) 1091: else 1092: clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]).freeze) 1093: end 1094: end
Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.
DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo
You can use placeholders in your SQL and provide arguments for those placeholders:
DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo
You can also provide a method name and arguments to call to get the SQL:
DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)
Note that datasets that specify custom SQL using this method will generally ignore future dataset methods that modify the SQL used, as specifying custom SQL overrides Sequel‘s SQL generator. You should probably limit yourself to the following dataset methods when using this method, or use the implicit_subquery extension:
# File lib/sequel/dataset/query.rb, line 1158 1158: def with_sql(sql, *args) 1159: if sql.is_a?(Symbol) 1160: sql = public_send(sql, *args) 1161: else 1162: sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty? 1163: end 1164: clone(:sql=>sql) 1165: end
Add the dataset to the list of compounds
# File lib/sequel/dataset/query.rb, line 1170 1170: def compound_clone(type, dataset, opts) 1171: if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds? 1172: s, ds = hoist_cte(dataset) 1173: return s.compound_clone(type, ds, opts) 1174: end 1175: ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze) 1176: opts[:from_self] == false ? ds : ds.from_self(opts) 1177: end
Return true if the dataset has a non-nil value for any key in opts.
# File lib/sequel/dataset/query.rb, line 1180 1180: def options_overlap(opts) 1181: !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty? 1182: end
Whether this dataset is a simple select from an underlying table, such as:
SELECT * FROM table SELECT table.* FROM table
# File lib/sequel/dataset/query.rb, line 1191 1191: def simple_select_all? 1192: return false unless (f = @opts[:from]) && f.length == 1 1193: o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)} 1194: from = f.first 1195: from = from.expression if from.is_a?(SQL::AliasedExpression) 1196: 1197: if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)} 1198: case o.length 1199: when 1 1200: true 1201: when 2 1202: (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll) 1203: else 1204: false 1205: end 1206: else 1207: false 1208: end 1209: end
These methods all return booleans, with most describing whether or not the dataset supports a feature.
Whether this dataset quotes identifiers.
# File lib/sequel/dataset/features.rb, line 12 12: def quote_identifiers? 13: @opts.fetch(:quote_identifiers, true) 14: end
Whether you must use a column alias list for recursive CTEs, false by default.
# File lib/sequel/dataset/features.rb, line 24 24: def recursive_cte_requires_column_aliases? 25: false 26: end
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer), false by default.
# File lib/sequel/dataset/features.rb, line 36 36: def requires_placeholder_type_specifiers? 37: false 38: end
Whether the dataset supports common table expressions, false by default. If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.
# File lib/sequel/dataset/features.rb, line 43 43: def supports_cte?(type=:select) 44: false 45: end
Whether the dataset supports common table expressions in subqueries, false by default. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.
# File lib/sequel/dataset/features.rb, line 50 50: def supports_cte_in_subqueries? 51: false 52: end
Whether the database supports derived column lists (e.g. "table_expr AS table_alias(column_alias1, column_alias2, …)"), true by default.
# File lib/sequel/dataset/features.rb, line 57 57: def supports_derived_column_lists? 58: true 59: end
Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.
# File lib/sequel/dataset/features.rb, line 88 88: def supports_intersect_except? 89: true 90: end
Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.
# File lib/sequel/dataset/features.rb, line 93 93: def supports_intersect_except_all? 94: true 95: end
Whether the dataset supports the IS TRUE syntax, true by default.
# File lib/sequel/dataset/features.rb, line 98 98: def supports_is_true? 99: true 100: end
Whether the dataset supports the JOIN table USING (column1, …) syntax, true by default. If false, support is emulated using JOIN table ON (table.column1 = other_table.column1).
# File lib/sequel/dataset/features.rb, line 104 104: def supports_join_using? 105: true 106: end
Whether limits are supported in correlated subqueries, true by default.
# File lib/sequel/dataset/features.rb, line 114 114: def supports_limits_in_correlated_subqueries? 115: true 116: end
Whether modifying joined datasets is supported, false by default.
# File lib/sequel/dataset/features.rb, line 124 124: def supports_modifying_joins? 125: false 126: end
Whether offsets are supported in correlated subqueries, true by default.
# File lib/sequel/dataset/features.rb, line 135 135: def supports_offsets_in_correlated_subqueries? 136: true 137: end
Whether the dataset supports pattern matching by regular expressions, false by default.
# File lib/sequel/dataset/features.rb, line 146 146: def supports_regexp? 147: false 148: end
Whether the dataset supports REPLACE syntax, false by default.
# File lib/sequel/dataset/features.rb, line 151 151: def supports_replace? 152: false 153: end
Whether the database supports SELECT *, column FROM table, true by default.
# File lib/sequel/dataset/features.rb, line 167 167: def supports_select_all_and_column? 168: true 169: end
Whether the dataset supports timezones in literal timestamps, false by default.
# File lib/sequel/dataset/features.rb, line 172 172: def supports_timestamp_timezones? 173: false 174: end
Whether the dataset supports fractional seconds in literal timestamps, true by default.
# File lib/sequel/dataset/features.rb, line 177 177: def supports_timestamp_usecs? 178: true 179: end
These methods don‘t fit cleanly into another section.