[Python知识库]Django orm使用记录

以以下例子为基础做一些记录

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import models

# Create your models here.



#班级主表(一)
class Clazz(models.Model):
    cno = models.AutoField(primary_key=True)
    cname = models.CharField(max_length=30)



#学生表（从表 多）
class Student(models.Model):
    sno = models.AutoField(primary_key=True)
    sname = models.CharField(max_length=30)
    cno = models.ForeignKey(Clazz,on_delete=models.CASCADE,db_constraint=False)

    def __unicode__(self):
        return u'Student:%s'%self.sname

# insertData('wangwu','Oracle','MySQL')

class Course(models.Model):
    course_no = models.AutoField(primary_key=True)
    course_name = models.CharField(max_length=30)

    def __unicode__(self):
        return u'Course:%s'%self.course_name

class Teacher(models.Model):
    tno = models.AutoField(primary_key=True)
    tname = models.CharField(max_length=30)
    cour = models.ManyToManyField(Course,db_constraint=False)

    def __unicode__(self):
        return u'Teacher:%s'%self.tname


一对一：OneToOneField
一对多： ForeignKey
多对多 ：ManyToManyField

参数 db_constraint=False 使用可以取消外键约束，

替代主键AutoField 自增的有限的替代方法是 uuid，
主要有2种方法 ：
一是使用原生的UUID，
uuid：使用原生UUIDField，导入 import uuid
设置如下： sno=models.UUIDField(default = uuid.uuid4,auto_created = True,editable = False)

二是使用ShortUUIDField
安装 pip install django-shortuuidfield
需要导入  from shortuuidfield import ShortUUIDField
设置如下：
 uid = ShortUUIDField(primary_key=True,auto_created = True)


###用例编号to_field 指向脚本实例用例编号，不要同时用db_constraint=False否则只能手动添加外键