5. Operators

5.1. Common Operators

Skylark maps these common operators (shown in examples):

Expressions	SQL string
User.id < 3	user.id < 3
User.id > 3	user.id > 3
User.id <= 3	user.id <= 3
User.id >= 3	user.id >= 3
User.id == 3	user.id = 3
User.id != 3	user.id <> 3
User.id + 2	user.id + 2
User.id - 2	user.id - 2
User.id * 2	user.id * 2
User.id / 2	user.id / 2
User.id % 2	user.id % 2
User.name.like(‘a%’)	user.name like ‘a%’
User.id._in(1, 2, 3)	user.id in (1, 2, 3)
User.id.not_in(1, 2)	user.id not in (1, 2)
User.id.between(3, 6)	user.id between 3 and 6
expression & expression	expression and expression
expression | expression	expression or expression

And the invert version is also valid for exchangeable operators(like +, -..):

>>> query = User.where(3 > User.id).select(User.name)
>>> query.sql
<sql 'select user.name from user where user.id < ?' (3,)>

>>> query = User.select(1 + User.id)
>>> query.sql
<sql 'select ? + user.id from user' (1,)>

5.2. Custom Operator

The method op() can help us build custom operators(such as bitwise operators).

An example for logical and &:

>>> query = User.select(User.id.op('&')(1))
>>> query.sql
<sql 'select user.id & ? from user' (1,)>

And an example for logical invert ~:

>>> from skylark import sql
>>> query = User.select(sql('').op('~')(User.id))
>>> query.sql
<sql 'select ~ user.id from user' ()>

5.3. Applicable objects

All common operators and method op() can be used with these objects: sql, field, function, expression.