建表

# -*- coding: UTF-8 -*-
from . import db

#多對多關係表，兩組一對多，即為多對多
class Boy2Girl(db.Model):
    __tablename__ = 'boy2girl'
    nid = db.Column(db.Integer,primary_key=True)
    #建立一對多關係，ForeignKey傳入對應表的__tablename__.id
    boy_id = db.Column(db.Integer,db.ForeignKey('boy.id'))
    # 建立一對多關係，ForeignKey傳入對應表的__tablename__.id
    girl_id = db.Column(db.Integer,db.ForeignKey('girl.id'))

class Boy(db.Model):
    __tablename__ = 'boy'
    id = db.Column(db.Integer,primary_key=True)
    name = db.Column(db.String(32),unique=True)
    age = db.Column(db.Integer)
    #並不會在資料庫中生成列，作用為ORM呼叫時可以通過.來呼叫另一張表
    #例如boy.girl，girl.boy
    #傳入的引數為另一張表的類名，關係表的表名，反向查詢時的名字，可以為任意名字
    girl = db.relationship('Girl',secondary = Boy2Girl.__tablename__,backref = 'boy')
    car = db.relationship('Car',backref = 'boy')
    def __repr__(self):
        return '<Boy %r>'%self.name

class Girl(db.Model):
    __tablename__ = 'girl'
    id = db.Column(db.Integer,primary_key=True)
    name = db.Column(db.String(32),unique=True)
    age = db.Column(db.Integer)


    def __repr__(self):
        return '<Girl %r>' % self.name

class Car(db.Model):
    __tablename__ = 'car'
    id = db.Column(db.Integer,primary_key=True)
    name = db.Column(db.String(32),unique=True)
	#建立一對多關係，ForeignKey傳入對應表的__tablename__.id，寫在多的一對多中多的那邊
    boy_id = db.Column(db.Integer,db.ForeignKey('boy.id'))

    def __repr__(self):
        return '<Car %r>'%self.name