本篇对于python操作Mysql主要有两种情况
·原生模块 pymsql
·ORM框架 SQLAchemy
pymysql
pymsql是python中操作的MYsql的模块,其使用方法和MySQLdb几乎相同
下载安装
1丶pip3 install pymsql
使用操作：
1·执行SQL
conn= pymsql.connect(host = "127.0.0.1",post = 3306,user = "root",passwd = "123",db = "t1")
#创建连接
cursor = conn.cursor()
#创建游标
effect_row = cursor.execute("updata host set host = "1.1.1.2"")
#执行SQL，并返回受影响行数
effect_row = cursor.execute("update host set = '1.1.1.2' where nid > %s",(1,))
#执行SQL，并返回受影响行数
effect_row = cursor.executemany("insert info host(host,color_id)values(%s,%s)",[("1.1.1.11",1)("1.1.1.11",2)])
#执行SQL，并返回受影响行数
conn.commit()
#提交,不然无法保存新建或者修改的数据
cursor.close()
#关闭游标
conn.close()
#关闭连接
2丶获取创建数据自增ID
#!/use/bin/evn python
# -*- coding:utf-8 -*-
import pymsql
conn = pymsql.connect(host= "127.0.0.1",port= 3306,user= "root",passwd="123",db="t1")
cursor = conn.cursor()
cursor.executemanty("insert info hosts(host,color_id)values(%s,%s)",[("1.1.1.11",1),("1.1.1.11",2)])
conn.commit()
cursor.colose()
conn.close()
#获取最新自增ID
new_id = cursor.lastrowid
3丶获取查询数据
#!/use/bin/env python
# -*- coding:utf-8 -*-
import pymsql
conn = pymsql.connect(host="127.0.0.1",post=3306,user='root',passwd='123',db='t1')
cursor = conn.cursor()
cursor.execute('select * from hosts')
row_1 = cursor.fetchone()
#获取第一行数据
row_2 = cursor.fetchmany(3)
#获取前N行数据
row_3 = cursor.fetchall()
#获取所有数据
conn.commit()
cursor.close()
conn.close()
注：在fetch数据时按照顺序进行,可以使用cursor.scroll(num,mode)来移动游标位置,如：
·cursoe.scroll(1,mode='relative') #相对当前位置移动
·cursor.scroll(2,mode="absolute") #相对绝对位置移动
4丶fetch数据类型
关于默认获取的数据是元祖类型,如果想要或者字典类型的数据,即：
#!/use/bin/env python
# -*- coding:utf-8 -*-
import pymsql
conn = pymsql.connect(host='127.0.0.1',port=3306,user='root',passwb='12
3',db='t1')
#游标设置为字典类型
cursor = conn.cursor(cursor=pymsql.cursor.DictCursor)
r = cursor.execute("call p1()")
result = cursor.fetchone()
conn.commit()
cursor.close()
conn.close()
SQLAchemy
SQLAchemy是python编程语言下的一款ORM框架，该框架建立 在数据库API之上,使用关系对象映射进行数据库操作,简言之便是：将对象转换成SQL,然后使用数据API执行SQL并获取执行结果·
安装：
pip3 install SQLAlchemy
SQLAlchemy本身无法操作数据库,其必须依赖pymysql等第三方插件,Dialect用于和数据API进行交流,根据配置文件的不同，调用不同的数据库API,从而实现对数据库的操作,如;
My SQL - Python
mysql+mysldb://<user>:<password>@<host>[:<post>]/<dbname>
pymsql
mysql+pymsql://<username>:<password>@<host>/<dbname>[?<options>]
MySQL - Connector
mysql + mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
cx_Oracle
oracle+cx_oracle://user:pass@host:port/dbname[?key=value*key=value...]
更多详见:http://docs.sqlalchemy.org/en/latest/dialects/index.html
一丶内部处理
使用 Engine/ConnectionPooling/Dialect 进行数据库操作，Engine使用ConnectionPooling连接数据库，然后再通过Dialect执行SQL语句。
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) # 执行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES ('1.1.1.22', 3)" # ) # 新插入行自增ID # cur.lastrowid # 执行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES(%s, %s)",[('1.1.1.22', 3),('1.1.1.221', 3),] # ) # 执行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES (%(host)s, %(color_id)s)", # host='1.1.1.99', color_id=3 # ) # 执行SQL # cur = engine.execute('select * from hosts') # 获取第一行数据 # cur.fetchone() # 获取第n行数据 # cur.fetchmany(3) # 获取所有数据 # cur.fetchall()
二、ORM功能使用
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。
1、创建表
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) Base = declarative_base() # 创建单表 class Users(Base): __tablename__ = 'users' id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(16)) __table_args__ = ( UniqueConstraint('id', 'name', name='uix_id_name'), Index('ix_id_name', 'name', 'extra'), ) # 一对多 class Favor(Base): __tablename__ = 'favor' nid = Column(Integer, primary_key=True) caption = Column(String(50), default='red', unique=True) class Person(Base): __tablename__ = 'person' nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) favor_id = Column(Integer, ForeignKey("favor.nid")) # 多对多 class Group(Base): __tablename__ = 'group' id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) port = Column(Integer, default=22) class Server(Base): __tablename__ = 'server' id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) class ServerToGroup(Base): __tablename__ = 'servertogroup' nid = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey('server.id')) group_id = Column(Integer, ForeignKey('group.id')) def init_db(): Base.metadata.create_all(engine) def drop_db(): Base.metadata.drop_all(engine)
注：设置外检的另一种方式 ForeignKeyConstraint(['other_id'], ['othertable.other_id'])
2、操作表
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) Base = declarative_base() # 创建单表 class Users(Base): __tablename__ = 'users' id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(16)) __table_args__ = ( UniqueConstraint('id', 'name', name='uix_id_name'), Index('ix_id_name', 'name', 'extra'), ) def __repr__(self): return "%s-%s" %(self.id, self.name) # 一对多 class Favor(Base): __tablename__ = 'favor' nid = Column(Integer, primary_key=True) caption = Column(String(50), default='red', unique=True) def __repr__(self): return "%s-%s" %(self.nid, self.caption) class Person(Base): __tablename__ = 'person' nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) favor_id = Column(Integer, ForeignKey("favor.nid")) # 与生成表结构无关，仅用于查询方便 favor = relationship("Favor", backref='pers') # 多对多 class ServerToGroup(Base): __tablename__ = 'servertogroup' nid = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey('server.id')) group_id = Column(Integer, ForeignKey('group.id')) group = relationship("Group", backref='s2g') server = relationship("Server", backref='s2g') class Group(Base): __tablename__ = 'group' id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) port = Column(Integer, default=22) # group = relationship('Group',secondary=ServerToGroup,backref='host_list') class Server(Base): __tablename__ = 'server' id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) def init_db(): Base.metadata.create_all(engine) def drop_db(): Base.metadata.drop_all(engine) Session = sessionmaker(bind=engine) session = Session()
3丶基本操作
obj = Users(name="alex0", extra='sb') session.add(obj) session.add_all([ Users(name="alex1", extra='sb'), Users(name="alex2", extra='sb'), ]) session.commit()
session.query(Users).filter(Users.id > 2).delete()
session.commit()
session.query(Users).filter(Users.id > 2).update({"name" : "099"})
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")
session.commit()
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()
# 条件 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()
更多功能参见文档，猛击这里下载PDF
