day12 python学习随笔 下

步骤三：

使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有组件对数据进行操作。根据类创建对象，对象转换成SQL，执行SQL。




#!/usr/bin/env python

# -*- coding:utf-8 -*-

from  sqlalchemy.ext.declarative  import  declarative_base
from  sqlalchemy  import  Column, Integer, String
from  sqlalchemy.orm  import  sessionmaker
from  sqlalchemy  import  create_engine

engine  =  create_engine( "mysql+mysqldb://root:[email protected]:3306/s11" , max_overflow = 5 )

Base  =  declarative_base()


class  User(Base):
    __tablename__  =  'users'
    id  =  Column(Integer, primary_key = True )
    name  =  Column(String( 50 ))

# 寻找Base的所有子类，按照子类的结构在数据库中生成对应的数据表信息
# Base.metadata.create_all(engine)

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


# ########## 增 ##########
# u = User(id=2, name='sb')
# session.add(u)
# session.add_all([
#     User(id=3, name='sb'),
#     User(id=4, name='sb')
# ])
# session.commit()

# ########## 删除 ##########
# session.query(User).filter(User.id > 2).delete()
# session.commit()

# ########## 修改 ##########
# session.query(User).filter(User.id > 2).update({'cluster_id' : 0})
# session.commit()
# ########## 查 ##########
# ret = session.query(User).filter_by(name='sb').first()

# ret = session.query(User).filter_by(name='sb').all()
# print ret

# ret = session.query(User).filter(User.name.in_(['sb','bb'])).all()
# print ret

# ret = session.query(User.name.label('name_label')).all()
# print ret,type(ret)

# ret = session.query(User).order_by(User.id).all()
# print ret

# ret = session.query(User).order_by(User.id)[1:3]
# print ret
# session.commit()