| Module | Sequel::SQL::ComplexExpressionMethods |
| In: |
lib/sequel/sql.rb
|
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
Extract a datetime_part (e.g. year, month) from self:
:date.extract(:year) # SQL: 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.
# File lib/sequel/sql.rb, line 243
243: def extract(datetime_part)
244: Function.new(:extract, PlaceholderLiteralString.new("#{datetime_part} FROM ?", [self])).sql_number
245: end
Return a BooleanExpression representation of self.
# File lib/sequel/sql.rb, line 248
248: def sql_boolean
249: BooleanExpression.new(:NOOP, self)
250: end
Return a NumericExpression representation of self.
# File lib/sequel/sql.rb, line 253
253: def sql_number
254: NumericExpression.new(:NOOP, self)
255: end
Return a StringExpression representation of self.
# File lib/sequel/sql.rb, line 258
258: def sql_string
259: StringExpression.new(:NOOP, self)
260: end