1、filter_by写条件
session.query(Users).filter_by(name='lqz').all()
2、between 、in_
session.query(Users).filter(Users.id.between(1, 10)).all()ret = session.query(Users).filter(Users.id.in_([1, 4, 5])).all()
3、~非，除...外
session.query(Users).filter(~Users.id.in_([1, 3, 5])).all()
4、二次筛选
session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='lqz'))).all()
5、and_、or_ 条件
from sqlalchemy import and_, or_# ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'zhangsan')).all() ret = session.query(Users).filter(Users.id > 3, Users.name == 'lqz').all() # 根上面一样# select * from users where id<=2 or name =lqz; ret = session.query(Users).filter(or_(Users.id <= 2, Users.name == 'zhangsan')).all()# select * from users where id <2 or (name=lqz and id>3) or extra !=''; ret = session.query(Users).filter(or_(Users.id < 2,and_(Users.name == 'zhangsan', Users.id > 3),Users.extra != "")).all()
6、like
# # 通配符，以e开头，不以e开头
# select * from users where name like l%;
ret = session.query(Users).filter(Users.name.like('z%')).all()
ret = session.query(Users).filter(~Users.name.like('l%')).all()
7、限制、分页
ret = session.query(Users)[1:2]
8、升序、降序
# ret = session.query(Users).order_by(Users.id.desc()).all() # 降序 # ret = session.query(Users).order_by(Users.id.asc()).all() # 升序 ret = session.query(Users).order_by(Users.id).all() # order_by 默认就是升序排序# 第一个条件重复后，再按第二个条件升序排 ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()
9、分组
from sqlalchemy.sql import func # select name from users group by name; 一旦分组,只能查询 分组字段和聚合函数的字段 ret = session.query(Users.name).group_by(Users.name).all()# #分组之后取最大id，id之和，最小id 和名字 ret = session.query(func.max(Users.id),func.sum(Users.id),func.min(Users.id), func.count(Users.id), Users.name).group_by(Users.name).all()
10、haviing筛选
# select max(id),sum(id),min(id),count(id),name from users group by name where id >5 having min(id)>2; ret = session.query(func.max(Users.id),func.sum(Users.id),func.min(Users.id),func.count(Users.id),Users.name).filter(Users.id > 2).group_by(Users.name).having(func.min(Users.id) > 5).all()
11、连表（默认用forinkey关联）
# select * from person,hobby where user.hobby_id=hobby.id; ret = session.query(Person, Hobby).filter(Person.hobby_id == Hobby.id).all()
12、join表，默认是inner join
# select * from person inner join hobby on person.hobby_id=hobby.id; ret = session.query(Person).join(Hobby).all()# # isouter=True 外连，表示Person left join Hobby，没有右连接，反过来即可 # select * from person left join hobby on person.hobby_id=hobby.id; ret = session.query(Person).join(Hobby, isouter=True).all() ret = session.query(Hobby).join(Person, isouter=True).all() # 右链接
13、union和union all
union 会去重
q1 = session.query(Boy.name).filter(Boy.id > 1) q2 = session.query(Girl.name).filter(Girl.id < 10) ret = q1.union(q2).all()q1 = session.query(Boy.name).filter(Boy.id > 1) q2 = session.query(Girl.name).filter(Girl.id < 10) ret = q1.union_all(q2).all()
