sqlalchemy_外键连接表

import sqlalchemy
from sqlalchemy import create_engine #连接数据库
from sqlalchemy.ext.declarative import declarative_base #orm基类
from sqlalchemy import Column,Integer,String,DATE,ForeignKey#Column列
from sqlalchemy.orm import sessionmaker,relationship
engine=create_engine("mysql+pymysql://root:[email protected]/wupeiqi",
                     encoding='utf-8',echo=False)#连接数据库 echo=TRUE输出执行过程

base=declarative_base()# 生成基类

class Student(base):
    __tablename__="student"
    id=Column(Integer,primary_key=True)
    name=Column(String(32),nullable=False)
    register_date=Column(DATE,nullable=False)
    def __repr__(self):
        return "<%s name:%s>"%(self.id,self.name)

class StudyRecord(base):
    __tablename__="study_record"
    id = Column(Integer, primary_key=True)
    day=Column(Integer,nullable=False)
    status=Column(String(32),nullable=False)
    stu_id=Column(Integer,ForeignKey('student.id')) #外键关联到student的id
    #StudyRecord通过student字段查询Student表里所有数据  在内存里建立relationship关系
    student=relationship("Student",backref="my_study_record")#允许你可以在student表里通过my_study_record字段反查Studyrecord所有数据
    def __repr__(self):
        return "<%s day:%s status:%s>"%(self.student.name,self.day,self.status)
base.metadata.create_all(engine)#创建表

#连接mysql
Session_class = sessionmaker(bind=engine)  # 创建与数据库的连接session class ,注意,这里返回给session的是个class,不是实例
session = Session_class()  # 生成session实例 session会话 类似cursor
'''
#插入数据
s1=Student(name="kobe",register_date="2017-05-16")
s2=Student(name="jack",register_date="2017-04-16")
s3=Student(name="duncon",register_date="2017-06-16")
s4=Student(name="Allen",register_date="2017-07-16")

record_1=StudyRecord(day=1,status="YES",stu_id=1)
record_2=StudyRecord(day=2,status="NO",stu_id=1)
record_3=StudyRecord(day=3,status="YES",stu_id=1)
record_4=StudyRecord(day=1,status="YES",stu_id=2)

session.add_all([s1,s2,s3,s4,record_1,record_2,record_3,record_4])
session.commit()
'''
#外键查询数据
stu_obj=session.query(Student).filter(Student.name=="kobe").first()
print(stu_obj.my_study_record)