python 之sqlalchemy many to one
Posted 曾春云
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通过查询多个父亲,对应一个儿子
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_engine 10 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() # 打开数据连接 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)
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