Python sqlalchemy orm 外鍵關聯

建立外鍵關聯 並經過relationship 互相調用

如圖：

 

實現代碼：

import sqlalchemy

# 調用連接數據庫
from sqlalchemy import create_engine
# 調用基類Base
from sqlalchemy.ext.declarative import declarative_base
# 調用Column建立字段 加類型
from sqlalchemy import Column, Integer, String,DATE,ForeignKey
# 調用操做連接,反查
from sqlalchemy.orm import sessionmaker,relationship

# create_engine 連接數據庫 mysql+pymysql:連接對象//用戶名:密碼@主機/DB
# encoding='utf-8' 連接字符集 ，echo=True 把全部信息打印出來
engine = create_engine("mysql+pymysql://root:123456@192.168.1.154/xiang",encoding='utf-8',
                       #echo=True
                       )

# 生成orm基類
Base = declarative_base()

class Student(Base):
    __tablename__ = "student"

    # 設置id爲主鍵
    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"

    # 設置id爲主鍵
    id = Column(Integer,primary_key=True)
    day = Column(Integer,nullable=False)
    status = Column(String(32),nullable=False)

    # 將student表的id字段 設置爲外鍵
    stu_id = Column(Integer,ForeignKey("student.id"))

    # -容許你在Student表裏經過backref字段反向查出全部它在表裏的關聯項-
    # study_record表 經過student字段查找Student表內全部字段
    # student表 經過my_study_record來訪問study_record表內字段
    # 注：relationship是orm本身經過在內存中類對象關聯實現。
    student = relationship("Student", backref="my_study_record")

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

#---------------1.建立表-----------------#
# 建立表結構
# Base.metadata.create_all(engine)
#---------------------------------------#

# bind=engine 綁定engine socket實例
Session_class = sessionmaker(bind=engine)

# 生成session實例，如同pymysql內的cursor
Session = Session_class()

#---------------2.插入數據-----------------#

# Student 建立插入數據
# s1 = Student(name="kevin",register_date="2014-05-21")
# s2 = Student(name="Jack",register_date="2014-05-22")
# s3 = Student(name="Rain",register_date="2014-05-23")
# s4 = Student(name="Eric",register_date="2014-05-24")

# StudyRecord 建立插入數據
# 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)

# 批量插入字段數據
# Session.add_all([s1,s2,s3,s4,study_obj1,study_obj2,study_obj3,study_obj4,])
#---------------------------------------#


#---------------3.查看數據-----------------#
# 指定查看"kevin"學員
stu_obj = Session.query(Student).filter(Student.name=="kevin").first()
print(stu_obj.my_study_record)
#---------------------------------------#


# 執行事務
Session.commit()