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  • SQLAlchemy 几种查询方式总结

    几种常见sqlalchemy查询:
    
        #简单查询
        print(session.query(User).all())
        print(session.query(User.name, User.fullname).all())
        print(session.query(User, User.name).all())
        
        #带条件查询
        print(session.query(User).filter_by(name='user1').all())
        print(session.query(User).filter(User.name == "user").all())
        print(session.query(User).filter(User.name.like("user%")).all())
        
        #多条件查询
        print(session.query(User).filter(and_(User.name.like("user%"), User.fullname.like("first%"))).all())
        print(session.query(User).filter(or_(User.name.like("user%"), User.password != None)).all())
        
        #sql过滤
        print(session.query(User).filter("id>:id").params(id=1).all())
        
        #关联查询 
        print(session.query(User, Address).filter(User.id == Address.user_id).all())
        print(session.query(User).join(User.addresses).all())
        print(session.query(User).outerjoin(User.addresses).all())
        
        #聚合查询
        print(session.query(User.name, func.count('*').label("user_count")).group_by(User.name).all())
        print(session.query(User.name, func.sum(User.id).label("user_id_sum")).group_by(User.name).all())
        
        #子查询
        stmt = session.query(Address.user_id, func.count('*').label("address_count")).group_by(Address.user_id).subquery()
        print(session.query(User, stmt.c.address_count).outerjoin((stmt, User.id == stmt.c.user_id)).order_by(User.id).all())
        
        #exists
        print(session.query(User).filter(exists().where(Address.user_id == User.id)))
        print(session.query(User).filter(User.addresses.any()))
    限制返回字段查询
    
    person = session.query(Person.name, Person.created_at,                     
                 Person.updated_at).filter_by(name="zhongwei").order_by(            
                 Person.created_at).first()
    记录总数查询:
    
    from sqlalchemy import func
    
    # count User records, without
    # using a subquery.
    session.query(func.count(User.id))
    
    # return count of user "id" grouped
    # by "name"
    session.query(func.count(User.id)).
            group_by(User.name)
    
    from sqlalchemy import distinct
    
    # count distinct "name" values
    session.query(func.count(distinct(User.name)))
    

     https://my.oschina.net/freegeek/blog/222725 

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  • 原文地址:https://www.cnblogs.com/hedianzhan/p/9643058.html
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