【Python】sqlalchemy 实现同一表 多级inner join

表结构

表名： vaguelabeluser  用户模糊标签表

字段：

vaguelabel_id 标签id

user_id  用户id

value 标签的值

原sql语句

select b.user_id from 

(vaguelabeluser b inner join vaguelabeluser a on a.user_id=b.user_id)

inner join vaguelabeluser c on b.user_id = c.user_id

where (b.vaguelabel_id=7 ) and (a.vaguelabel_id=2) and (c.vaguelabel_id=3)

group by b.user_id;

Python语句

from app.BehaviorLabels import sqlModel  #自己写的，详见下方【附录1】

from from sqlalchemy import create_engine, and_, or_

from sqlalchemy.orm import sessionmaker,aliased

# 链接数据库

engine = create_engine('mysql+pymysql://root:root@localhost:3306/behaviorDB?charset=utf8')

Session = sessionmaker(bind=engine)

dbsession = Session()

#由于是同表，需要定义表的别名

vg = sqlModel.VagueLabelUser  #已经定义过的 类，详见下方【附录1】

vg1 = aliased(sqlModel.VagueLabelUser)

vg2 = aliased(sqlModel.VagueLabelUser)

#查询

#这里查询了 数量，和上面的sql语句有些区别

count = dbsession.query(vg.user_id).join(vg1, vg.user_id == vg1.user_id).join(vg2, vg.user_id == vg2.user_id).filter(

                and_(vg.vaguelabel_id == 7,

                vg1.vaguelabel_id == 2,

                vg2.vaguelabel_id == 3)

           ).group_by(vg.user_id).count()

【附录1】app.BehaviorLabels sqlModel.py

# coding:utf8

import datetimefrom sqlalchemy

import create_engine# 会话

from sqlalchemy.orm import sessionmaker# 定义

from sqlalchemy import Column, String, Integer, DateTime, Float, Boolean, TIMESTAMP, func,PickleType

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy.orm import relationship

from sqlalchemy import ForeignKey

# 链接数据库

engine = create_engine('mysql+pymysql://root:root@localhost:3306/behaviorDB?charset=utf8')

print(">>", engine)

# 定义数据库

Base = declarative_base()



class VagueLabelUser(Base):

    __tablename__ = "VagueLabelUser"

    id = Column(Integer, primary_key=True)

    # 外键

    user_id = Column(Integer, ForeignKey('InitialUser.user_id'), comment="关联User表")

    vaguelabel_id = Column(Integer, ForeignKey('VagueLabels.id'), comment="关联标签表")

    # 值

    vague_value = Column(Float,default=0)

    comment = Column(String(30))

    type = Column(Integer,comment="用于扩展")

    # 时间戳

    createtime = Column(TIMESTAMP(True), server_default=func.now(), comment='创建时间')

    updatetime = Column(TIMESTAMP(True), nullable=False, server_default=func.now(), onupdate=func.now(), comment='修改时间')

    # 标志位

    validflag = Column(Boolean, default=1, comment="有效位标志 0：无效 1：有效")

    def __repr__(self):

        return '%s(%r)' % (self.__class__.__name__, self.id)