SQLAchemy
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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。
pip install SQLAlchemy
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(): #执行删除表操作 Base.metadata.drop_all(engine) init_db() #执行建表操作
操作表
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): # 自定义返回值 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() # 增 obj = Users(name="alex0", extra=\'sb\') session.add(obj) session.add_all([ Users(name="alex1", extra=\'sb\'), Users(name="alex2", extra=\'sb\'), ]) session.commit() # 删 session.query(Users).filter(Users.id > 2).delete() session.commit() # 改 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") #synchronize_session=\'evaluate\'设置Users.num+1为数字相加 session.commit() # 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() # 条件查 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() # 通配符查 ret = session.query(Users).filter(Users.name.like(\'e%\')).all() ret = session.query(Users).filter(~Users.name.like(\'e%\')).all() # 限制查 ret = session.query(Users)[1:2] # 排序查 ret = session.query(Users).order_by(Users.name.desc()).all() ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all() # 分组查 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() # 连表查 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就是left join,想要right join就换个位置。 # 组合查 q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union(q2).all() #union默认去重 q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union_all(q2).all() #union_all不去重
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