Sqlalchemy

配置数据库MySQL-Python

    mysql+mysqldb://:@[:]/
 
pymysql
    mysql+pymysql://:@/[?]
 

from sqlalchemy.engine import create_engine

ngine = create_engine("mysql+pymysql://root:[email protected]/sqldb",
                       encoding='utf8')

 

原生sql

# engine.execute(
#     "insert into ts_test values ('alex',2)"
# )
res = engine.execute('select*from ts_test')
print(res.fetchall())

 

 

Orm

创建表

def init_db():
    Base.metadata.create_all(engine)
 
def drop_db():
    Base.metadata.drop_all(engine)

from sqlalchemy.engine import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, String, Integer, ForeignKey, UniqueConstraint, Index

engine = create_engine("mysql+pymysql://root:[email protected]/sqldb",
                       encoding='latin1', echo=True)
Base = declarative_base() ##########单表############## class Users(Base): 
　　__tablename__ = 'user' id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(32)) __table_args__ = ( UniqueConstraint('id', 'name', name='uix_id_name'), ###联合唯一索引 Index('ix_id_name', 'name', 'extra'), #######普通索引 )


#######一对多###########

class Class(Base):
    __tablename__ = 'class'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    user_id = Column(Integer, ForeignKey('user.id'))

########多对多#############

class Hobby(Base):
    __tablename__ = 'hobby'
    id = Column(Integer,primary_key=True)
    class_id = Column(Integer,ForeignKey('class.id'))
    user_id = Column(Integer,ForeignKey('user.id'))

 

 

 查询表

from sqlal import models
from sqlalchemy.orm import sessionmaker

Session = sessionmaker(bind=models.engine)
session = Session()

#####增######
obj = models.Users(name='alex', extra='三年级小屁孩')

session.add_all([
    Users(name="alex1", extra='sb'),
    Users(name="alex2", extra='sb'),
])

session.add(obj) session.commit()


######删#######

session.query(Users).filter(Users.id > 2).delete()      #不能是first()
session.commit()

#########改##########

city_2 = session.query(models.City).filter_by(name='鹰').update({'name':'鹰'})

# 相加时类名.字段 = 类名.字段 + xxx

session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")

########查#############

ret = session.query(Users).all()
ret = session.query(Users.name, Users.extra).all()
ret = session.query(Users).filter_by(name='alex').all()
ret = session.query(Users).filter_by(name='alex').first()

ret = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(User.id).all()

ret = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()

 

其他：

ret = session.query(Users).filter_by(name='alex').all()
ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()
ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()
ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()
ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()
ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()
from sqlalchemy import and_, or_
ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
ret = session.query(Users).filter(
    or_(
        Users.id < 2,
        and_(Users.name == 'eric', Users.id > 3),
        Users.extra != ""
    )).all()


# 通配符
ret = session.query(Users).filter(Users.name.like('e%')).all()
ret = session.query(Users).filter(~Users.name.like('e%')).all()

# 限制
ret = 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()

# 分组
from sqlalchemy.sql import func

ret = session.query(Users).group_by(Users.extra).all()
ret = session.query(
    func.max(Users.id),
    func.sum(Users.id),
    func.min(Users.id)).group_by(Users.name).all()

ret = session.query(
    func.max(Users.id),
    func.sum(Users.id),
    func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()

# 连表

ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()

ret = session.query(Person).join(Favor).all()

ret = session.query(Person).join(Favor, isouter=True).all()


# 组合
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()