day12_04 mysql外键单文件

Posted 2021-06-06 flytoyou

import sqlalchemy
from sqlalchemy import create_engine, func, Enum, DATE, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://root:alex3714@192.168.56.12/oldboy",
                       encoding=\'utf-8\')#,echo=True)

Base = declarative_base()  # 生成orm基类

class Student(Base):
    __tablename__ = \'student\'  # 表名
    id = Column(Integer, primary_key=True,unique=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\'  # 表名
    id = Column(Integer, primary_key=True,unique=True)
    day = Column(Integer)
    status = Column(String(32),nullable=False)
    stu_id = Column(Integer,ForeignKey("student.id"))   #创建外键


    #允许你在study_record表里通过student字段反向查出所有它在student表里的关联项
    #允许通过my_study_record查找study_record表里的关联项
    student = relationship("Student", backref="my_study_record")



    def __repr__(self):
        return "<%s day:%s status:%s>" % (self.student.name,self.day,self.status)


Base.metadata.create_all(engine)  # 创建表结构

Session_class = sessionmaker(bind=engine)  # 创建与数据库的会话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

#插入数据
\'\'\'
s1 = Student(name="Alex",register_date="2014-05-21")
s2 = Student(name="Jack",register_date="2014-03-21")
s3 = Student(name="Rain",register_date="2014-02-21")
s4 = Student(name="Eric",register_date="2014-01-21")

session.add_all([s1,s2,s3,s4])

study_obj1 = StudyRecord(day=1,status="YES",stu_id=1)
study_obj2 = StudyRecord(day=2,status="NO",stu_id=1)
study_obj3 = StudyRecord(day=3,status="YES",stu_id=1)
study_obj4 = StudyRecord(day=1,status="YES",stu_id=2)

session.add_all([study_obj1,study_obj2,study_obj3,study_obj4])

session.commit()

\'\'\'

# 实例化 student = Student()
# study_obj = query(id=1)
# student = query(Student).filter(Student.id == stu_obj.stu_id).first()
stu_obj = session.query(Student).filter(Student.name=="alex").first()
# 允许你在study_record表里通过student字段反向查出所有它在student表里的关联项
# 允许通过my_study_record查找study_record表里的关联项

print(stu_obj)  #study_record表查找student表


print(stu_obj.my_study_record)  #student表查找study_record表

session.commit()