Module: Sequel::SQL::ComplexExpressionMethods

Included in:
Dataset, LiteralString, GenericComplexExpression, GenericExpression, Symbol
Defined in:
lib/sequel/sql.rb

Overview

Adds methods that allow you to treat an object as an instance of a specific ComplexExpression subclass. This is useful if another library overrides the methods defined by Sequel.

For example, if Symbol#/ is overridden to produce a string (for example, to make file system path creation easier), the following code will not do what you want:

:price/10 > 100

In that case, you need to do the following:

:price.sql_number/10 > 100

Instance Method Summary collapse

Instance Method Details

#extract(datetime_part) ⇒ Object

Extract a datetime_part (e.g. year, month) from self:

:date.extract(:year) # extract(year FROM "date")

Also has the benefit of returning the result as a NumericExpression instead of a generic ComplexExpression.

The extract function is in the SQL standard, but it doesn’t doesn’t use the standard function calling convention, and it doesn’t work on all databases.



339
340
341
 
# File 'lib/sequel/sql.rb', line 339

def extract(datetime_part)
  NumericExpression.new(:extract, datetime_part, self)
end

#sql_boolean ⇒ Object

Return a BooleanExpression representation of self.



344
345
346
 
# File 'lib/sequel/sql.rb', line 344

def sql_boolean
  BooleanExpression.new(:NOOP, self)
end

#sql_number ⇒ Object

Return a NumericExpression representation of self.

~:a # NOT "a"
~:a.sql_number # ~"a"



352
353
354
 
# File 'lib/sequel/sql.rb', line 352

def sql_number
  NumericExpression.new(:NOOP, self)
end

#sql_string ⇒ Object

Return a StringExpression representation of self.

:a + :b # "a" + "b"
:a.sql_string + :b # "a" || "b"



360
361
362
 
# File 'lib/sequel/sql.rb', line 360

def sql_string
  StringExpression.new(:NOOP, self)
end