models.py
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column
from sqlalchemy import Integer,String,Text,Date,DateTime
from sqlalchemy import create_engine
Base = declarative_base()
class Users(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String(32), index=True, nullable=False)
def create_all():
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/s9day120?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）
)
Base.metadata.create_all(engine)
def drop_all():
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/s9day120?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）
)
Base.metadata.drop_all(engine)
if __name__ == '__main__':
create_all()
views.py
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Users
# 创建引擎
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/s9day120?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）
)
# 根据引擎创建session工厂
SessionFactory = sessionmaker(bind=engine)
# 用session工厂创建一个session对象
session = SessionFactory()
..........
# 根据Users类对users表进行增删改查
..........
# 关闭session
session.close()
行操作
增
obj = Users(name='alex')
session.add(obj)
session.commit()
session.add_all([
Users(name='小东北'),
Users(name='龙泰')
])
session.commit()
删
session.query(Users).filter(Users.id >= 2).delete()
session.commit()
改
session.query(Users).filter(Users.id == 4).update({Users.name:'东北'})
session.query(Users).filter(Users.id == 4).update({'name':'小东北'})
session.query(Users).filter(Users.id == 4).update({'name':Users.name+"DSB"},synchronize_session=False)
session.commit()
查
result = session.query(Users).all()
for row in result:
print(row.id,row.name)
result = session.query(Users).filter(Users.id >= 2)
for row in result:
print(row.id,row.name)
result = session.query(Users).filter(Users.id >= 2).first()
print(result)
其他常用操作
-
指定查询列
result = session.query(Users.id,Users.name.label('cname')).all()
for item in result:
print(item[0],item.id,item.cname)
-
多个查询条件（默认and）
session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()
-
between
session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()
-
in
session.query(Users).filter(Users.id.in_([1,3,4])).all()
session.query(Users).filter(~Users.id.in_([1,3,4])).all(） # 非
-
子查询
session.query(Users).filter(Users.id.in_(session.query(Users.id).filter(Users.name=='eric'))).all()
-
and和or
from sqlalchemy import and_, or_
session.query(Users).filter(Users.id > 3, Users.name == 'eric').all()
session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
session.query(Users).filter(
or_(
Users.id < 2,
and_(Users.name == 'eric', Users.id > 3),
Users.extra != ""
)).all()
-
filter_by
session.query(Users).filter_by(name='alex').all()
-
通配符
ret = session.query(Users).filter(Users.name.like('e%')).all()
ret = session.query(Users).filter(~Users.name.like('e%')).all()
-
切片
result = session.query(Users)[1:2]
-
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()
-
group by
ret = session.query(
Users.depart_id,
func.count(Users.id),
).group_by(Users.depart_id).all()
for item in ret:
print(item)
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)
-
union和union all
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret = q1.union(q2).all()
q1 = session.query(Users.name).filter(Users.id > 2)
q2 = session.query(Favor.caption).filter(Favor.nid < 2)
ret = q1.union_all(q2).all()
