pymsql是python中操作mysql的模块，其使用方法和mysqldb几乎相同
一、下载安装
pip3 install pymysql
二、操作使用
1、执行SQL
立即学习“Python免费学习笔记（深入）”；
#!/usr/bin/env python# -*- coding:utf-8 -*-import pymysql # 创建连接conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')# 创建游标cursor = conn.cursor() # 执行SQL，并返回收影响行数effect_row = cursor.execute("update hosts set host = '1.1.1.2'") # 执行SQL，并返回受影响行数#effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,)) # 执行SQL，并返回受影响行数#effect_row = cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)]) # 提交，不然无法保存新建或者修改的数据conn.commit() # 关闭游标cursor.close()# 关闭连接conn.close()
登录后复制
2、获取新创建数据自增ID
#!/usr/bin/env python# -*- coding:utf-8 -*-import pymysql conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')cursor = conn.cursor()cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])conn.commit()cursor.close()conn.close() # 获取最新自增IDnew_id = cursor.lastrowid
登录后复制
3、获取查询数据
#!/usr/bin/env python# -*- coding:utf-8 -*-import pymysql conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')cursor = conn.cursor()cursor.execute("select * from hosts") # 获取第一行数据row_1 = cursor.fetchone() # 获取前n行数据# row_2 = cursor.fetchmany(3)# 获取所有数据# row_3 = cursor.fetchall() conn.commit()cursor.close()conn.close()
登录后复制
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：
cursor.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、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：
#!/usr/bin/env python# -*- coding:utf-8 -*-import pymysql conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1') # 游标设置为字典类型cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)r = cursor.execute("call p1()") result = cursor.fetchone() conn.commit()cursor.close()conn.close()
登录后复制
SQLAlchemy
SQLAlchemy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，其必须以来pymsql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：
MySQL-Python mysql+mysqldb://:@[:]/ pymysql mysql+pymysql://:@/[?] MySQL-Connector mysql+mysqlconnector://:@[:]/ cx_Oracle oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
登录后复制
一、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()
登录后复制
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_basefrom sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Indexfrom sqlalchemy.orm import sessionmaker, relationshipfrom 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'])
登录后复制
2、操作表
#!/usr/bin/env python# -*- coding:utf-8 -*-from sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Indexfrom sqlalchemy.orm import sessionmaker, relationshipfrom sqlalchemy import create_engineengine = 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()
登录后复制
obj = Users(name="alex0", extra='sb')session.add(obj)session.add_all([ Users(name="alex1", extra='sb'), Users(name="alex2", extra='sb'),])session.commit()
登录后复制
session.query(Users).filter(Users.id > 2).delete() session.commit()
登录后复制
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()
登录后复制
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()
登录后复制
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 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 funcret = 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)q2 = session.query(Favor.caption).filter(Favor.nid
登录后复制
版权声明：本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容， 请发送邮件至253000106@qq.com举报，一经查实，本站将立刻删除。
发布者：PHP中文网，转转请注明出处：https://www.chuangxiangniao.com/p/2282356.html
