from sqlalchemy.orm import sessionmaker

from sqlalchemy import create_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 in result:

        print(row.id,row.name)

# 根据条件查询

result = session.query(Users).filter(Users.id >= 2)

for row in result:

        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 in result:

        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 import and_, 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 import func

ret = session.query(

        Users.depart_id,

        func.count(Users.id),

).group_by(Users.depart_id).all()

for item in ret:

        print(item)

# having

from sqlalchemy.sql import func

ret = session.query(

        Users.depart_id,

        func.count(Users.id),

).group_by(Users.depart_id).having(func.count(Users.id) >= 2).all()

for item in ret:

        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()