如何修复django.db.utils.IntegrityError:在django 3.x中插入或删除表

从今天早上开始，我开始

django.db.utils.IntegrityError:在表“Department\u course”上插入或更新违反外键 约束“部门\课程\课程\类型\ id \ 71e71f3c \ fk \部门” 详细信息：表“部门课程类型”中没有键（课程类型id）=（UG）。

迁移django模型时出错。帮我解决这个问题，伙计们

今天早上，我尝试用department model的外键创建另外两个模型。从那时起，这个问题就开始了。但是现在我删除了这两个模型。但我还是犯了同样的错误。帮我修一下

型号.py

from django.db import models

# Create your models here.
class departments(models.Model):
    # department = models.CharField(max_length = 40, null = True)
    name = models.CharField(max_length=40, unique=True, primary_key = True)
    img = models.ImageField(upload_to="Dept_img", null = True)
    desc = models.TextField(null = True)

    def __str__(self):
        return self.name

class department_detail(models.Model):
    name = models.OneToOneField(departments, on_delete=models.CASCADE, null = True)
    About = models.TextField(null = True)

    def __str__(self):
        return self.name.name


class course(models.Model):
    COURSE = (
        ('UG','UG'),
        ('PG','PG')
        )
    Department_name = models.ForeignKey(departments, on_delete=models.CASCADE, null = True)
    Course_type = models.CharField(null=True, max_length=40, choices=COURSE, default = None)
    Course_name = models.CharField(null = True, max_length=80)
    Course_duration = models.CharField(null=True, max_length=30)

    def  __str__(self):
        return self.Department_name.name

class carousel(models.Model):
    Department = models.ForeignKey(departments,on_delete=models.CASCADE, null = True)
    Image = models.ImageField(upload_to='Carousel', null = True)
    Img_title = models.CharField(max_length=30, null=True)
    Img_desc = models.CharField(max_length=500, null=True)
    date_created = models.DateTimeField(auto_now_add=True, null=True)



    def __str__(self):
        return self.Department.name

---

你能展示你的项目树吗？对不起，兄弟，我不明白你的意思？从cource>Department\u name中删除null=True这可能会对你有所帮助（对于carousel、Department\u详细模型也是如此）

Department\u name=models.ForeignKey（departments，on\u delete=models.CASCADE）

然后尝试迁移它。尝试仍不工作brother@Løvýlýhíñësh在模型之外保持航向，然后尝试。