sqlalchemy 单表增删改查

from sqlalchemy.orm importsessionmaker
from sqlalchemy importcreate_engine

engine =create_engine(
        "mysql+pymysql://root:密码@127.0.0.1:3306/数据库?charset=utf8",
        max_overflow=0,  #超过连接池大小外最多创建的连接
        pool_size=5,  #连接池大小
        pool_timeout=30,  #池中没有线程最多等待的时间，否则报错
        pool_recycle=-1  #多久之后对线程池中的线程进行一次连接的回收（重置）
)

SessionFactory = sessionmaker(bind=engine)

session = SessionFactory()

#单条
obj = Users(name='tom')
session.add(obj)
session.commit()
#多条
session.add_all([
        Users(name='海贼王'),
        Users(name='死神')
])
session.commit()
session.close()

session.query(Users).filter(Users.id >= 2).delete()
session.commit()
session.close()

session.query(Users).filter(Users.id == 4).update({Users.name:'死神'})
session.query(Users).filter(Users.id == 4).update({'name':'火影'})
#在原本的字段，修改属性
session.query(Users).filter(Users.id == 4).update({'name':Users.name+"DSB"},synchronize_session=False)
session.commit()
session.close()

#查询所有
result =session.query(Users).all()
for row inresult:
        print(row.id,row.name)
#根据条件查询
result = session.query(Users).filter(Users.id >= 2)
for row inresult:
        print(row.id,row.name)
#查询id大于2的第一个对象
result = session.query(Users).filter(Users.id >= 2).first()
print(result)

查询一条数据
ret = session.query(User).filter(User.id == 1).one()
print(ret.id, ret.name)

#1. 指定列, 字段别名#select id,name as cname from users;
result = session.query(Users.id,Users.name.label('cname')).all()
for item inresult:
        print(item[0],item.id,item.cname)
#2. 默认条件and
session.query(Users).filter(Users.id > 1, Users.name == 'abc').all()
#3. between
session.query(Users).filter(Users.id.between(1, 3), Users.name == 'abc').all()
#4. in, not in ~
session.query(Users).filter(Users.id.in_([1,3,4])).all()
session.query(Users).filter(~Users.id.in_([1,3,4])).all()
#5. 子查询
session.query(Users).filter(Users.id.in_(session.query(Users.id).filter(Users.name=='abc'))).all()
#6. and 和 or
from sqlalchemy importand_, or_
#默认 and
session.query(Users).filter(Users.id > 3, Users.name == 'eric').all()
#and
session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
#or
session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
#and or 一起使用
session.query(Users).filter(
    or_(
        Users.id < 2,
        and_(Users.name == 'eric', Users.id > 3),
        Users.extra != "")).all()

#7. filter_by，查询内部执行的是filter
session.query(Users).filter_by(name='abc').all()

#8. 通配符 % 任意个， _一个
ret = session.query(Users).filter(Users.name.like('a_')).all()
ret = session.query(Users).filter(~Users.name.like('e%')).all()

#9. 切片/分页
result = session.query(Users)[1:2]

#10.排序
ret =session.query(Users).order_by(Users.name.desc()).all()
ret =session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()

#11. group by, having , 聚合函数
from sqlalchemy.sql importfunc

ret =session.query(
        Users.depart_id,
        func.count(Users.id),
).group_by(Users.depart_id).all()
for item inret:
        print(item)

#having
from sqlalchemy.sql importfunc

ret =session.query(
        Users.depart_id,
        func.count(Users.id),
).group_by(Users.depart_id).having(func.count(Users.id) >= 2).all()
for item inret:
        print(item)

#12.union 和 union all, unuon 去重 union all 不去重
"""select id,name from users
UNION
select id,name from users;
"""
#去重
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret =q1.union(q2).all()
#不去重
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret = q1.union_all(q2).all()

session.close()

session.commit()