时间:2021-07-01 10:21:17 帮助过:9人阅读
注:查看数据库连接:show status like ‘Threads%‘;
步骤二:
使用 Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 进行数据库操作。Engine使用Schema Type创建一个特定的结构对象,之后通过SQL Expression Language将该对象转换成SQL语句,然后通过 ConnectionPooling 连接数据库,再然后通过 Dialect 执行SQL,并获取结果。
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#!/usr/bin/env python
# -*- coding:utf-8 -*-
from sqlalchemy import create_engine, Table, Column, Integer, String, MetaData, ForeignKey
metadata = MetaData()
user = Table( ‘user‘ , metadata,
Column( ‘id‘ , Integer, primary_key = True ),
Column( ‘name‘ , String( 20 )),
)
color = Table( ‘color‘ , metadata,
Column( ‘id‘ , Integer, primary_key = True ),
Column( ‘name‘ , String( 20 )),
)
engine = create_engine( "mysql+mysqldb://root:123@127.0.0.1:3306/s11" , max_overflow = 5 )
metadata.create_all(engine)
# metadata.clear()
# metadata.remove()
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更多内容详见:
http://www.jianshu.com/p/e6bba189fcbd
http://docs.sqlalchemy.org/en/latest/core/expression_api.html
注:SQLAlchemy无法修改表结构,如果需要可以使用SQLAlchemy开发者开源的另外一个软件Alembic来完成。
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。
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#!/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:123@127.0.0.1:3306/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()
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更多功能参见文档,猛击这里下载PDF
数据库统一API--SQLAlchemy
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