Python（9） Python 操作 MySQL 之 pysql 与 SQLAchemy_mysql

• 一、pymsql
• 二、SQLAlchemy

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()

#!/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ID new_id = cursor.lastrowid

#!/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()

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

# 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()

# 利用with定义函数      @contextlib.contextmanager     def mysql(self, host='127.0.0.1', port=3306, user='nick', passwd='', db='db1', charset='utf8'):         self.conn = pymysql.connect(host=host, port=port, user=user, passwd=passwd, db=db, charset=charset)         self.cuersor = self.conn.cursor(cursor=pymysql.cursors.DictCursor)          try:             yield self.cuersor         finally:             self.conn.commit()             self.cuersor.close()             self.conn.close()  # 执行 with mysql() as cuersor:    print(cuersor)    # 操作MySQL代码块

pip3 install SQLAlchemy

MySQL-Python     mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>     pymysql     mysql+pymysql://<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

#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy import create_engine       engine = create_engine("mysql+pymysql://root:[email protected]: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()

View Code

#!/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  # 指定字符集、最大连接池数 engine = create_engine("mysql+pymysql://root:[email protected]:3306/suoning4?charset=utf8", max_overflow=5)  Base = declarative_base()  # 创建单表 class Users(Base):     # 表名     __tablename__ = 'users'     # 表字段     id = Column(Integer, primary_key=True)  # 主键、默认自增     name = Column(String(32))     extra = Column(String(16))      __table_args__ = (     UniqueConstraint('id', 'name', name='uix_id_name'), # 唯一索引     Index('ix_id_name', 'name', 'extra'),   # 普通索引     )      def __repr__(self):         # 查是输出的内容格式，本质还是对象         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) # 默认值、唯一索引      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):     # 关系表要放对应表上面，否则找不到     __tablename__ = 'servertogroup'     nid = Column(Integer, primary_key=True, autoincrement=True)     server_id = Column(Integer, ForeignKey('server.id'))    # 外键     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) # 不能为空     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) # 自增     hostname = Column(String(64), unique=True, nullable=False)   def init_db():     # 创建表     Base.metadata.create_all(engine)  def drop_db():     # 删除表     Base.metadata.drop_all(engine)

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  # 指定字符集、最大连接池数 engine = create_engine("mysql+pymysql://root:[email protected]:3306/suoning4?charset=utf8", max_overflow=5)  Base = declarative_base()  # 创建单表 class Users(Base):     # 表名     __tablename__ = 'users'     # 表字段     id = Column(Integer, primary_key=True)  # 主键、默认自增     name = Column(String(32))     extra = Column(String(16))      __table_args__ = (     UniqueConstraint('id', 'name', name='uix_id_name'), # 唯一索引     Index('ix_id_name', 'name', 'extra'),   # 普通索引     )      def __repr__(self):         # 查是输出的内容格式，本质还是对象         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) # 默认值、唯一索引      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):     # 关系表要放对应表上面，否则找不到     __tablename__ = 'servertogroup'     nid = Column(Integer, primary_key=True, autoincrement=True)     server_id = Column(Integer, ForeignKey('server.id'))    # 外键     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) # 不能为空     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) # 自增     hostname = Column(String(64), unique=True, nullable=False)   def init_db():     # 创建表     Base.metadata.create_all(engine)  def drop_db():     # 删除表     Base.metadata.drop_all(engine)   # 先实例化sessionmaker类，Session对象加括号执行类下的__call__方法， # 得到session对象，所以session可以调用Session类下的add，add_all等方法 Session = sessionmaker(bind=engine) # 指定引擎 session = Session()

# 增  # 添加一条 obj = Users(name="张三", extra='三儿') session.add(obj) # 添加多条 session.add_all([     Users(name="李四", extra='四儿'),     Users(name="汪五", extra='五儿'), ]) # 提交 session.commit()

# 删  session.query(Users).filter(Users.id > 2).delete() session.query(Users).filter_by(id = 1).delete() session.commit()

# 改  session.query(Users).filter(Users.id > 2).update({"name" : "nick"}) session.query(Users).filter(Users.id > 2).update({"name" : "nick", "extra":"niubily"}) session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "Suo"}, synchronize_session=False) session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate") session.commit()

# 查 # all()结果为对象列表，first()为具体对象  ret = session.query(Users).all() ret = session.query(Users.name, Users.extra).all() ret = session.query(Users).filter_by(name='nick').all() ret = session.query(Users).filter_by(name='nick').first() print(ret)

#　条件 ret = session.query(Users).filter_by(name='nick').all() ret = session.query(Users).filter(Users.id > 1, Users.name == 'nick').all() ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'nick').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='nick'))).all()  from sqlalchemy import and_, or_        # 导入模块 ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'nick')).all() ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'nick')).all() ret = session.query(Users).filter(     or_(         Users.id < 2,         and_(Users.name == 'nick', Users.id > 3),         Users.extra != ""     )).all()   # 通配符 ret = session.query(Users).filter(Users.name.like('n%')).all() ret = session.query(Users).filter(~Users.name.like('n%')).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        # 导入模块  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()  # isouter=True 理解为 left join ，如果不写为 inner join  # 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()