摘要
SQLAlchemy 几种查询方式总结
几种常见sqlalchemy查询：
#简单查询
print(session.query(User).all()) print(session.query(User.name, User.fullname).all()) print(session.query(User, User.name).all())#带条件查询print(session.query(User).filter_by(name='user1').all()) print(session.query(User).filter(User.name =="user").all()) print(session.query(User).filter(User.name.like("user%")).all())#多条件查询print(session.query(User).filter(and_(User.name.like("user%"), User.fullname.like("first%"))).all()) print(session.query(User).filter(or_(User.name.like("user%"), User.password !=None)).all())#sql过滤print(session.query(User).filter("id>:id").params(id=1).all())#关联查询print(session.query(User, Address).filter(User.id == Address.user_id).all()) print(session.query(User).join(User.addresses).all()) print(session.query(User).outerjoin(User.addresses).all())#聚合查询print(session.query(User.name, func.count('*').label("user_count")).group_by(User.name).all()) print(session.query(User.name, func.sum(User.id).label("user_id_sum")).group_by(User.name).all())#子查询stmt = session.query(Address.user_id, func.count('*').label("address_count")).group_by(Address.user_id).subquery() print(session.query(User, stmt.c.address_count).outerjoin((stmt, User.id == stmt.c.user_id)).order_by(User.id).all())#existsprint(session.query(User).filter(exists().where(Address.user_id == User.id))) print(session.query(User).filter(User.addresses.any()))
限制返回字段查询
person= session.query(Person.name, Person.created_at,Person.updated_at).filter_by(name="zhongwei").order_by(Person.created_at).first()
记录总数查询：
from sqlalchemyimportfunc#countUserrecords, without# using a subquery.session.query(func.count(User.id))#returncountof user"id"grouped# by"name"session.query(func.count(User.id)).\ group_by(User.name)from sqlalchemyimportdistinct#countdistinct"name"valuessession.query(func.count(distinct(User.name)))
