1. many-to-one

1.1 What is the relationship of many to one ？

A class , There are many students in a class , Just like the foreign keys in the table

class Major(models.Model):
    major_name = models.CharField(max_length=20,verbose_name=' Major name ')
    class Meta:
        verbose_name = ' Professional watch '
        verbose_name_plural = verbose_name
        db_table = 'major'
    def __str__(self):
        return self.major_name
class Student(models.Model):
    stu_name = models.CharField(max_length=20,verbose_name=' The student's name ')
    score = models.IntegerField(verbose_name=' achievement ')
    sex = models.CharField(max_length=2,verbose_name=' Gender ')
    major = models.ForeignKey(Major,on_delete=models.CASCADE,verbose_name=' Major number ')
    class Meta:
        verbose_name = ' Student list '
        verbose_name_plural = verbose_name
        db_table = 'student'
    def __str__(self):
        return self.stu_name

1.2 Many to one addition, deletion and modification

increase

    def post(self,request):
        name = request.POST.get('name')
        score = request.POST.get('score')
        sex = request.POST.get('sex')
        major = request.POST.get('major')
        try:
            Student.objects.create(
                stu_name = name,
                score = score,
                sex = sex,
                major_id = major
            )
        except Exception as e:
            print(e)
            return HttpResponse(' Add failure ')
        return redirect('/major/')

Delete

class DeleteView(View):
    def get(self,request,id):
        Student.objects.filter(id=id).delete()
        return redirect('/major/')

modify

class UpdateView(View):
    def get(self,request,id):
        try:
            stud_data = Student.objects.get(id=id)
        except Exception as e:
            print(e)
            return HttpResponse(' Failed to get data ')
        return render(request,'update.html',{'stus':stud_data})
    def post(self,request,id):
        name = request.POST.get('name')
        score = request.POST.get('score')
        sex = request.POST.get('sex')
        major = request.POST.get('major')
        try:
            Student.objects.filter(id=id).update(
                stu_name=name,
                score=score,
                sex=sex,
                major=major
            )
        except Exception as e:
            print(e)
            return HttpResponse(' Add failure ')
        return redirect('/major/')