Django怎样自定义model创建数据库索引的顺序

@python_2_unicode_compatible
class ZZ_Demo(models.Model): #此处的ZZ开头的命名是为了让这个class在最后创建
######中间什么都不要写######
 class Meta:
 verbose_name = '这是个Demo'
 verbose_name_plural = '这是个Demo' #这些是在Django admin里显示的 可忽略

 def __str__(self):
 return self.name

python manage.py makemigrations
python manage.py migrate

@python_2_unicode_compatible
class ZZ_Demo(models.Model):
 ab_productline = models.ForeignKey(ProductLine, verbose_name=u'产品线',default=1,null=True)
 ac_name = models.CharField(max_length=50, verbose_name = u'故障名称',null=True)
 ......
 bn_casetags = models.CharField(max_length=50, verbose_name = u'关键词 标签 备注',default=None,blank=True,null=True)

 class Meta:
 verbose_name = '这是个Demo'
 verbose_name_plural = '这是个Demo'

 def __str__(self):
 return self.be_casenumber

class Cart(models.Model):
 user = models.ForeignKey(
 MyUser,
 verbose_name="用户"
 )
 goods = models.ForeignKey(
 Goods,
 verbose_name="商品"
 )
 num = models.IntegerField(
 verbose_name="商品数量"
 )
 is_select = models.BooleanField(
 default=True,
 verbose_name="选中状态"
 )
 
 class Meta:
 # 联合约束 其中goods和user不能重复
 unique_together = ["goods", "user"]
 # 联合索引
 index_together = ["user", "goods"]