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[PHP] python操作SQL

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  • 发表于 2017-5-14 02:44:00 | 显示全部楼层 |阅读模式
    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
    #!/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()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ID new_id = cursor.lastrowid3、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()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()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://[u]:@[:]/ pymysql mysql+pymysql://[u]:@/[?] MySQL-Connector mysql+mysqlconnector://[u]:@[:]/ cx_Oracle oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]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()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()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()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 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) q2 = session.query(Favor.caption).filter(Favor.nid
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