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  • sqlalchemy 外键

    一、表

    from sqlalchemy.orm import relationship
    from sqlalchemy import Column
    from sqlalchemy import Integer,String,ForeignKey
    
    class Depart(Base):
        __tablename__ = 'depart'
        id = Column(Integer, primary_key=True)
        title = Column(String(32), index=True, nullable=False)
    
    class Users(Base):
        __tablename__ = 'users'
    
        id = Column(Integer, primary_key=True)
        name = Column(String(32), index=True, nullable=False)
        depart_id = Column(Integer,ForeignKey("depart.id"))
        # dp 创建联系,不创建字段
        dp = relationship("Depart", backref='pers')

    二、数据操作

    # 1. 查询所有用户+所属部门名称
    ret = session.query(Users.id,Users.name,Depart.title).join(Depart,Users.depart_id == Depart.id).all()
    for row in ret:
        print(row.id,row.name,row.title)
    
    # left join, sql语句
    query = session.query(Users.id,Users.name,Depart.title).join(Depart,Users.depart_id == Depart.id,isouter=True)
    print(query)
    
    # 2. relation字段:查询所有用户+所属部门名称 ====> 正向查询 推荐
    ret = session.query(Users).all()
    for row in ret:
        print(row.id,row.name,row.depart_id,row.dp.title)
    
    # 3. relation字段:查询销售部所有的人员  =======> 反向查询 推荐
    obj = session.query(Depart).filter(Depart.title == '销售').first()
    for row in obj.pers:
        print(row.id,row.name,obj.title)
    
    # 4. 创建一个名称叫:IT部门,再在该部门中添加一个员工:a
    # 方式一:
    d1 = Depart(title='IT')
    session.add(d1)
    session.commit()
    #
    u1 = Users(name='a',depart_id=d1.id)
    session.add(u1)
    session.commit()
    
    # 方式二:使用relation
    u1 = Users(name='a',dp=Depart(title='IT'))
    session.add(u1)
    session.commit()
    
    # 5. 创建一个名称叫:保洁的部门,再在该部门中添加多个员工:a/b/c
    d1 = Depart(title='保洁')
    d1.pers = [Users(name='a'),Users(name='b'),Users(name='c'),]
    session.add(d1)
    session.commit()
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  • 原文地址:https://www.cnblogs.com/wt7018/p/11617825.html
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