SQLAlchemy操作MariaDB笔记之三

查询语法练习

query方法返回的是一个可迭代输出的对象，可以索引和切片。参数可以为表对象，表的字段对象。

>>> for instance in session.query(User).order_by(User.id): ...     print instance.name, instance.fullname

>>> for name, fullname in session.query(User.name, User.fullname): ...     print name, fullname

给表对象起别名，同时可以指定字段的别名。

>>> from sqlalchemy.orm import aliased>>> user_alias = aliased(User, name='user_alias')SQL>>> for row in session.query(user_alias, user_alias.name).all(): ...    print row.user_alias

fillter_by()方法相当于where子句；order_by
方法相当于orderby子句；

子句中的符号：

query.filter(User.name == ‘ed’)

query.filter(User.name != ‘ed’)

LIKE

query.filter(User.name.like(‘%ed%’))

IN

query.filter(User.name.in_([‘ed’, ‘wendy’, ‘jack’]))

从句

query.filter(User.name.in_(
session.query(User.name).filter(User.name.like(‘%ed%’))
))

NOT IN

query.filter(~User.name.in_([‘ed’, ‘wendy’, ‘jack’]))

IS NULL

query.filter(User.name == None)

AND

from sqlalchemy import and_

query.filter(and_(User.name == ‘ed’, User.fullname == ‘Ed Jones’))

query.filter(User.name == ‘ed’, User.fullname == ‘Ed Jones’)

OR

query.filter(User.name == ‘ed’).filter(User.fullname == ‘Ed Jones’)

from sqlalchemy import or_
query.filter(or_(User.name == ‘ed’, User.name == ‘wendy’))

MATCH

query.filter(User.name.match(‘wendy’))