擅长:python、mysql、java
<p>删除<code>Sub_Specialization</code>它是多余的</p>
<p>使用<code>django-mptt</code><a href="https://django-mptt.github.io/django-mptt/models.html#setting-up-a-django-model-for-mptt" rel="nofollow">https://django-mptt.github.io/django-mptt/models.html#setting-up-a-django-model-for-mptt</a></p>
<p>和<code>django-mptt-admin</code><a href="https://github.com/mbraak/django-mptt-admin" rel="nofollow">https://github.com/mbraak/django-mptt-admin</a></p>