These methods are designed as replacements for the core extensions, so that Sequel is still easy to use if the core extensions are not enabled.
Create an SQL::AliasedExpression for the given expression and alias.
Sequel.as(:column, :alias) # "column" AS "alias"
# File lib/sequel/sql.rb, line 321 def as(exp, aliaz) SQL::AliasedExpression.new(exp, aliaz) end
Order the given argument ascending. Options:
:nulls |
Set to :first to use NULLS FIRST (so NULL values are ordered before other values), or :last to use NULLS LAST (so NULL values are ordered after other values). |
Sequel.asc(:a) # a ASC Sequel.asc(:b, :nulls=>:last) # b ASC NULLS LAST
# File lib/sequel/sql.rb, line 334 def asc(arg, opts={}) SQL::OrderedExpression.new(arg, false, opts) end
Return an SQL::Blob that holds the same data as this string. Blobs provide proper escaping of binary data. If given a blob, returns it directly.
# File lib/sequel/sql.rb, line 341 def blob(s) if s.is_a?(SQL::Blob) s else SQL::Blob.new(s) end end
Return an SQL::CaseExpression created with the given arguments.
Sequel.case([[{:a=>[2,3]}, 1]], 0) # SQL: CASE WHEN a IN (2, 3) THEN 1 ELSE 0 END Sequel.case({:a=>1}, 0, :b) # SQL: CASE b WHEN a THEN 1 ELSE 0 END
# File lib/sequel/sql.rb, line 353 def case(*args) # core_sql ignore SQL::CaseExpression.new(*args) end
Cast the reciever to the given SQL type. You can specify a ruby class as a type, and it is handled similarly to using a database independent type in the schema methods.
Sequel.cast(:a, :integer) # CAST(a AS integer) Sequel.cast(:a, String) # CAST(a AS varchar(255))
# File lib/sequel/sql.rb, line 362 def cast(arg, sql_type) SQL::Cast.new(arg, sql_type) end
Cast the reciever to the given SQL type (or the database's default Integer type if none given), and return the result as a NumericExpression, so you can use the bitwise operators on the result.
Sequel.cast_numeric(:a) # CAST(a AS integer) Sequel.cast_numeric(:a, Float) # CAST(a AS double precision)
# File lib/sequel/sql.rb, line 372 def cast_numeric(arg, sql_type = nil) cast(arg, sql_type || Integer).sql_number end
Cast the reciever to the given SQL type (or the database's default String type if none given), and return the result as a StringExpression, so you can use + directly on the result for SQL string concatenation.
Sequel.cast_string(:a) # CAST(a AS varchar(255)) Sequel.cast_string(:a, :text) # CAST(a AS text)
# File lib/sequel/sql.rb, line 382 def cast_string(arg, sql_type = nil) cast(arg, sql_type || String).sql_string end
Return an emulated function call for getting the number of characters in the argument:
Sequel.char_length(:a) # char_length(a) -- Most databases Sequel.char_length(:a) # length(a) -- SQLite
# File lib/sequel/sql.rb, line 391 def char_length(arg) SQL::EmulatedFunction.new(:char_length, arg) end
Return a DateAdd expression, adding an interval to the date/timestamp expr.
# File lib/sequel/extensions/date_arithmetic.rb, line 31 def date_add(expr, interval) DateAdd.new(expr, interval) end
Return a DateAdd expression, adding the negative of the interval to the date/timestamp expr.
# File lib/sequel/extensions/date_arithmetic.rb, line 37 def date_sub(expr, interval) interval = if interval.is_a?(Hash) h = {} interval.each{|k,v| h[k] = -v unless v.nil?} h else -interval end DateAdd.new(expr, interval) end
Return a delayed evaluation that uses the passed block. This is used to delay evaluations of the code to runtime. For example, with the following code:
ds = DB[:table].where{column > Time.now}
The filter is fixed to the time that where was called. Unless you are only using the dataset once immediately after creating it, that's probably not desired. If you just want to set it to the time when the query is sent to the database, you can wrap it in Sequel.delay:
ds = DB[:table].where{column > Sequel.delay{Time.now}}
Note that for dates and timestamps, you are probably better off using Sequel::CURRENT_DATE and Sequel::CURRENT_TIMESTAMP instead of this generic delayed evaluation facility.
# File lib/sequel/sql.rb, line 411 def delay(&block) raise(Error, "Sequel.delay requires a block") unless block SQL::DelayedEvaluation.new(block) end
Order the given argument descending. Options:
:nulls |
Set to :first to use NULLS FIRST (so NULL values are ordered before other values), or :last to use NULLS LAST (so NULL values are ordered after other values). |
Sequel.desc(:a) # b DESC Sequel.desc(:b, :nulls=>:first) # b DESC NULLS FIRST
# File lib/sequel/sql.rb, line 425 def desc(arg, opts={}) SQL::OrderedExpression.new(arg, true, opts) end
Wraps the given object in an appropriate Sequel wrapper. If the given object is already a Sequel object, return it directly. For condition specifiers (hashes and arrays of two pairs), true, and false, return a boolean expressions. For numeric objects, return a numeric expression. For strings, return a string expression. For procs or when the method is passed a block, evaluate it as a virtual row and wrap it appropriately. In all other cases, use a generic wrapper.
This method allows you to construct SQL expressions that are difficult to construct via other methods. For example:
Sequel.expr(1) - :a # SQL: (1 - a)
# File lib/sequel/sql.rb, line 441 def expr(arg=(no_arg=true), &block) if block_given? if no_arg return expr(block) else raise Error, 'cannot provide both an argument and a block to Sequel.expr' end elsif no_arg raise Error, 'must provide either an argument or a block to Sequel.expr' end case arg when Symbol t, c, a = Sequel.split_symbol(arg) arg = if t SQL::QualifiedIdentifier.new(t, c) else SQL::Identifier.new(c) end if a arg = SQL::AliasedExpression.new(arg, a) end arg when SQL::Expression, LiteralString, SQL::Blob arg when Hash SQL::BooleanExpression.from_value_pairs(arg, :AND) when Array if condition_specifier?(arg) SQL::BooleanExpression.from_value_pairs(arg, :AND) else SQL::Wrapper.new(arg) end when Numeric SQL::NumericExpression.new(:NOOP, arg) when String SQL::StringExpression.new(:NOOP, arg) when TrueClass, FalseClass SQL::BooleanExpression.new(:NOOP, arg) when Proc expr(virtual_row(&arg)) else SQL::Wrapper.new(arg) end end
Extract a datetime_part (e.g. year, month) from the given expression:
Sequel.extract(:year, :date) # extract(year FROM "date")
# File lib/sequel/sql.rb, line 494 def extract(datetime_part, exp) SQL::NumericExpression.new(:extract, datetime_part, exp) end
Returns a Sequel::SQL::Function with the function name and the given arguments.
Sequel.function(:now) # SQL: now() Sequel.function(:substr, :a, 1) # SQL: substr(a, 1)
# File lib/sequel/sql.rb, line 503 def function(name, *args) SQL::Function.new(name, *args) end
Return a Postgres::HStore proxy for the given hash.
# File lib/sequel/extensions/pg_hstore.rb, line 314 def hstore(v) case v when Postgres::HStore v when Hash Postgres::HStore.new(v) else # May not be defined unless the pg_hstore_ops extension is used hstore_op(v) end end
Return the object wrapped in an Postgres::HStoreOp.
# File lib/sequel/extensions/pg_hstore_ops.rb, line 308 def hstore_op(v) case v when Postgres::HStoreOp v else Postgres::HStoreOp.new(v) end end
Return the argument wrapped as an SQL::Identifier.
Sequel.identifier(:a__b) # "a__b"
# File lib/sequel/sql.rb, line 510 def identifier(name) SQL::Identifier.new(name) end
Create a BooleanExpression case insensitive (if the database supports it) pattern match of the receiver with the given patterns. See SQL::StringExpression.like.
Sequel.ilike(:a, 'A%') # "a" ILIKE 'A%'
# File lib/sequel/sql.rb, line 547 def ilike(*args) SQL::StringExpression.like(*(args << {:case_insensitive=>true})) end
Return a Sequel::SQL::StringExpression representing an SQL string made up of the concatenation of the given array's elements. If an argument is passed, it is used in between each element of the array in the SQL concatenation.
Sequel.join([:a]) # SQL: a Sequel.join([:a, :b]) # SQL: a || b Sequel.join([:a, 'b']) # SQL: a || 'b' Sequel.join(['a', :b], ' ') # SQL: 'a' || ' ' || b
# File lib/sequel/sql.rb, line 523 def join(args, joiner=nil) raise Error, 'argument to Sequel.join must be an array' unless args.is_a?(Array) if joiner args = args.zip([joiner]*args.length).flatten args.pop end return SQL::StringExpression.new(:NOOP, '') if args.empty? args = args.map do |a| case a when Symbol, ::Sequel::SQL::Expression, ::Sequel::LiteralString, TrueClass, FalseClass, NilClass a else a.to_s end end SQL::StringExpression.new(:'||', *args) end
Create a SQL::BooleanExpression case sensitive (if the database supports it) pattern match of the receiver with the given patterns. See SQL::StringExpression.like.
Sequel.like(:a, 'A%') # "a" LIKE 'A%'
# File lib/sequel/sql.rb, line 555 def like(*args) SQL::StringExpression.like(*args) end
Converts a string into a Sequel::LiteralString, in order to override string literalization, e.g.:
DB[:items].filter(:abc => 'def').sql #=> "SELECT * FROM items WHERE (abc = 'def')" DB[:items].filter(:abc => Sequel.lit('def')).sql #=> "SELECT * FROM items WHERE (abc = def)"
You can also provide arguments, to create a Sequel::SQL::PlaceholderLiteralString:
DB[:items].select{|o| o.count(Sequel.lit('DISTINCT ?', :a))}.sql #=> "SELECT count(DISTINCT a) FROM items"
# File lib/sequel/sql.rb, line 572 def lit(s, *args) # core_sql ignore if args.empty? if s.is_a?(LiteralString) s else LiteralString.new(s) end else SQL::PlaceholderLiteralString.new(s, args) end end
Return a Sequel::SQL::BooleanExpression created from the condition specifier, matching none of the conditions.
Sequel.negate(:a=>true) # SQL: a IS NOT TRUE Sequel.negate([[:a, true]]) # SQL: a IS NOT TRUE Sequel.negate([[:a, 1], [:b, 2]]) # SQL: ((a != 1) AND (b != 2))
# File lib/sequel/sql.rb, line 590 def negate(arg) if condition_specifier?(arg) SQL::BooleanExpression.from_value_pairs(arg, :AND, true) else raise Error, 'must pass a conditions specifier to Sequel.negate' end end
Return a Sequel::SQL::BooleanExpression created from the condition specifier, matching any of the conditions.
Sequel.or(:a=>true) # SQL: a IS TRUE Sequel.or([[:a, true]]) # SQL: a IS TRUE Sequel.or([[:a, 1], [:b, 2]]) # SQL: ((a = 1) OR (b = 2))
# File lib/sequel/sql.rb, line 604 def or(arg) if condition_specifier?(arg) SQL::BooleanExpression.from_value_pairs(arg, :OR, false) else raise Error, 'must pass a conditions specifier to Sequel.or' end end
Return a Postgres::PGArray proxy for the given array and database array type.
# File lib/sequel/extensions/pg_array.rb, line 572 def pg_array(v, array_type=nil) case v when Postgres::PGArray if array_type.nil? || v.array_type == array_type v else Postgres::PGArray.new(v.to_a, array_type) end when Array Postgres::PGArray.new(v, array_type) else # May not be defined unless the pg_array_ops extension is used pg_array_op(v) end end
Return the object wrapped in an Postgres::ArrayOp.
# File lib/sequel/extensions/pg_array_ops.rb, line 241 def pg_array_op(v) case v when Postgres::ArrayOp v else Postgres::ArrayOp.new(v) end end
Wrap the array or hash in a Postgres::JSONArray or Postgres::JSONHash.
# File lib/sequel/extensions/pg_json.rb, line 185 def pg_json(v) case v when Postgres::JSONArray, Postgres::JSONHash v when Array Postgres::JSONArray.new(v) when Hash Postgres::JSONHash.new(v) else raise Error, "Sequel.pg_json requires a hash or array argument" end end
Convert the object to a Postgres::PGRange.
# File lib/sequel/extensions/pg_range.rb, line 501 def pg_range(v, db_type=nil) case v when Postgres::PGRange if db_type.nil? || v.db_type == db_type v else Postgres::PGRange.new(v.begin, v.end, :exclude_begin=>v.exclude_begin?, :exclude_end=>v.exclude_end?, :db_type=>db_type) end when Range Postgres::PGRange.from_range(v, db_type) else # May not be defined unless the pg_range_ops extension is used pg_range_op(v) end end
Return the expression wrapped in the Postgres::RangeOp.
# File lib/sequel/extensions/pg_range_ops.rb, line 136 def pg_range_op(v) case v when Postgres::RangeOp v else Postgres::RangeOp.new(v) end end
Wraps the expr array in an anonymous Postgres::PGRow::ArrayRow instance.
# File lib/sequel/extensions/pg_row.rb, line 578 def pg_row(expr) case expr when Array Postgres::PGRow::ArrayRow.new(expr) else # Will only work if pg_row_ops extension is loaded pg_row_op(expr) end end
Return a PGRowOp wrapping the given expression.
# File lib/sequel/extensions/pg_row_ops.rb, line 165 def pg_row_op(expr) Postgres::PGRowOp.wrap(expr) end
Create a qualified identifier with the given qualifier and identifier
Sequel.qualify(:table, :column) # "table"."column" Sequel.qualify(:schema, :table) # "schema"."table" Sequel.qualify(:table, :column).qualify(:schema) # "schema"."table"."column"
# File lib/sequel/sql.rb, line 617 def qualify(qualifier, identifier) SQL::QualifiedIdentifier.new(qualifier, identifier) end
Return an SQL::Subscript with the given arguments, representing an SQL array access.
Sequel.subscript(:array, 1) # array[1] Sequel.subscript(:array, 1, 2) # array[1, 2] Sequel.subscript(:array, [1, 2]) # array[1, 2]
# File lib/sequel/sql.rb, line 627 def subscript(exp, *subs) SQL::Subscript.new(exp, subs.flatten) end
Return an emulated function call for trimming a string of spaces from both sides (similar to ruby's String#strip).
Sequel.trim(:a) # trim(a) -- Most databases Sequel.trim(:a) # ltrim(rtrim(a)) -- Microsoft SQL Server
# File lib/sequel/sql.rb, line 636 def trim(arg) SQL::EmulatedFunction.new(:trim, arg) end
Return a SQL::ValueList created from the given array. Used if the array contains all two element arrays and you want it treated as an SQL value list (IN predicate) instead of as a conditions specifier (similar to a hash). This is not necessary if you are using this array as a value in a filter, but may be necessary if you are using it as a value with placeholder SQL:
DB[:a].filter([:a, :b]=>[[1, 2], [3, 4]]) # SQL: (a, b) IN ((1, 2), (3, 4)) DB[:a].filter('(a, b) IN ?', [[1, 2], [3, 4]]) # SQL: (a, b) IN ((1 = 2) AND (3 = 4)) DB[:a].filter('(a, b) IN ?', Sequel.value_list([[1, 2], [3, 4]])) # SQL: (a, b) IN ((1, 2), (3, 4))
# File lib/sequel/sql.rb, line 649 def value_list(arg) raise Error, 'argument to Sequel.value_list must be an array' unless arg.is_a?(Array) SQL::ValueList.new(arg) end
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