python 之sqlalchemy many to one

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通過查詢多個父親，對應一個兒子

 1 #!/usr/bin/env python3 2 # -*- coding: utf-8 -*- 3 """ 4 @author: zengchunyun 5 """ 6 from sqlalchemy import Column, Integer, String, Float, DateTime, ForeignKey 7 from sqlalchemy.orm import sessionmaker, relationship, backref 8 from sqlalchemy.ext.declarative import declarative_base 9 from sqlalchemy import create_engine10 11 Base = declarative_base()12 engine = create_engine(‘mysql+pymysql://root:[email protected]:3306/day11‘,echo=True)13 14 15 16 class Parent(Base):17     __tablename__ = ‘parent‘18     id = Column(Integer, primary_key=True)19     name = Column(String(64))20     child_id = Column(Integer, ForeignKey("child.id"))21     childr = relationship("Child")22 23 24 class Child(Base):25     __tablename__ = ‘child‘26     id = Column(Integer, primary_key=True)27     name = Column(String(64))28 29 30 31 Base.metadata.create_all(engine)32 33 DBSession = sessionmaker()34 DBSession.configure(bind=engine)35 session = DBSession()  # 開啟資料連線36 37 38 39 40 ret = session.query(Parent).filter(Parent.name == ‘zeng‘).one()41 print(ret)42 print(ret.childr.name)43 ret = session.query(Parent).filter(Parent.name == ‘chunyun‘).one()44 print(ret)45 print(ret.childr.name)46 47 ret = session.query(Parent).filter(Parent.name == ‘chun‘).one()48 print(ret)49 print(ret.childr.name)

 

python 之sqlalchemy many to one