模型操作

① 在models.py中建立数据库模型

class StudentInfo(models.Model):
  address = models.CharField(max_length=50, null=True)
  phone = models.CharField(max_length=11, null=True)
  
  class Meta:
    db_table = 'stu_info'

class Grade(models.Model):
    g_name = models.CharField(max_length=100, null=True)

   class Meta:
     db_table = 'grade'

class Student(models.Model):
  s_name = models.CharField(max_length=10, unique=True, null=False)
  age = models.IntegerField(default=18)
   # 第一次创建数据时，自动默认为当前创建的时间
  create_time = models.DateTimeField(auto_now_add=True)
   # 修改时自动更新为修改的时间
  operate_time = models.DateTimeField(auto_now=True)
  is_delete = models.BooleanField(default=0)
  chinese = models.DecimalField(max_digits=3, decimal_places=1,null=True)
  math = models.DecimalField(max_digits=3, decimal_places=1,null=True)
  # 一对一字段，一个学生对应一条学生信息
  stuinfo = models.OneToOneField(StudentInfo, related_name='stu', on_delete=models.CASCADE, null=True)  
  # 多对多字段，
  grade = models.ForeignKey(Grade,related_name='stu',on_delete=models.CASCADE, null=True)
  class Meta:
    db_table = 'student'

在views.py中通过学生信息表查找学生信息

def sel_stu_by_info(request):
  if request.method == 'GET':
    stuinfo = StudentInfo.objects.filter(phone = '123456').first()
# 通过django自带的OneToOneField即可通过related_name自动创建外键关系
    stu = stuinfo.stu
  return HttpResponse('查询成功')

def add_grade(request):
    if request.method == 'GET':
        names = ['python班级', 'Java班级', 'Php班级', 'C++班级']
        for name in names:
            if not Grade.objects.filter(g_name=name).exists():
                Grade.objects.create(g_name=name)
        # 分配班级
        stus = Student.objects.filter(pk__in=[1, 2, 3, 4, 5]).all()
        g = Grade.objects.filter(g_name='python班级').first()
        for stu in stus:
            stu.grade = g
            #stu.grade_id = g.id
            stu.save()
        return HttpResponse('添加班级和学生信息')