MySQL— pymysql and SQLAlchemy

#在终端直接运行  pip3 install pymysql

#!/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，并返回受影响行数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()

#!/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()# 获取最新自增IDnew_id = cursor.lastrowid    cursor.close()  conn.close()

#!/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()

#!/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()

#在终端直接运行pip3 install SQLAlchemy

#!/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#表明依赖关系并创建连接，最大连接数为5 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'    # 表名    id = Column(Integer, primary_key=True,autoincrement=True)    # id列，主键自增    name = Column(String(32))    # name列    extra = Column(String(16))    # extra列       __table_args__ = (      UniqueConstraint('id', 'name', name='uix_id_name'),    # 创建联合唯一索引        Index('ix_id_name', 'name', 'extra'),    # 创建普通索引    )      # 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"))    # 创建外键    # 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'))    # 创建外键    group_id = Column(Integer, ForeignKey('group.id'))    # 创建外键    def init_db():      Base.metadata.create_all(engine)      def drop_db():      Base.metadata.drop_all(engine)

注：设置外键的另一种方式 ForeignKeyConstraint([‘other_id’], [‘othertable.other_id’])

#!/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'),      )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()

表结构 + 数据库连接

b.1 增

#单条增加obj = Users(name="alex0", extra='sb')  session.add(obj)#多条增加session.add_all([      Users(name="alex1", extra='sb'),      Users(name="alex2", extra='sb'),  ])#提交session.commit()

b.2 删

#先查询到要删除的记录，再deletesession.query(Users).filter(Users.id > 2).delete()  session.commit()

b.3 改

#先查询，再更新session.query(Users).filter(Users.id > 2).update({"name" : "099"})    # 直接更改session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)    # 字符串拼接session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")    # 数字相加session.commit()

b.4 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()

#　条件ret = session.query(Users).filter_by(name='alex').all()    # 条件内为关键字表达式ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()    # 条件内为SQL表达式ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()    # betweenret = session.query(Users).filter(Users.id.in_([1,3,4])).all()    # inret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()    # not inret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()    # 子查询条件from sqlalchemy import and_, or_  ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()    # andret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()    # orret = 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()    # e开头ret = session.query(Users).filter(~Users.name.like('e%')).all()    # 非e开头# 限制ret = session.query(Users)[1:2]    # 相当于limit# 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()    # 笛卡儿积连表ret = session.query(Person).join(Favor).all()    # 默认内连 inner joinret = session.query(Person).join(Favor, isouter=True).all()    # 左连# 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()