在postgres中创建表之间的外键关系

Question

我必须像下面这样的表格：

class BlogCategory(models.Model):
    name = models.CharField(max_length=255)

    class Meta:
        verbose_name = 'Blog category'
        verbose_name_plural = 'Blog categories'

    def __unicode__(self):
        return self.name


class Blog(models.Model):
    category = models.ForeignKey(BlogCategory, related_name="blogs", null=True, blank=True)

我想在 Blog 和 BlogCategory 之间创建外键关系。这是我对 postgres 的命令：

ALTER TABLE blog_blog ADD CONSTRAINT fk_blog_blogcategory FOREIGN KEY (category_id) REFERENCES blogcategory (name);

我得到一个错误：

ERROR:  column "category_id" referenced in foreign key constraint does not exist

Answer 1

可以试试这个：

ALTER TABLE blog_blog ADD CONSTRAINT fk_blog_blogcategory FOREIGN KEY (name) REFERENCES blogcategory (name);

Answer 2

运行在您的原始命令之前：

ALTER TABLE blog_blog ADD COLUMN category_id integer;

在postgres中创建表之间的外键关系

Create foreign key relation between tabels in postgres

database

postgresql

foreign-keys

relational-database