title: How to deal with order migrate file?
body: <p><strong>I have model:</strong></p>
  
  <pre class="lang-py prettyprint-override"><code>class Student(models.Model):
      name = models.CharField(max_length=255)
      extend = models.IntegerField(blank=True, null=True)
  </code></pre>
  
  <p>At <code>migration</code> file with name: <strong>005_remove_name</strong></p>
  
  <p>I have a function:</p>
  
  <pre class="lang-py prettyprint-override"><code>def remove_name(apps, schema_editor):
     Student = apps.get_model('myapp', 'Student')
     queryset = Student.objects.filter(name="Peter")
     if queryset:
          queryset.delete()
  
  </code></pre>
  
  <p>But during migrate operation, my screening show "missing column extend"</p>
  
  <p>I figure out that <strong>extend</strong> column in <strong>Student</strong> table will have been added at migration file with name : <strong>007_add_extend</strong>.</p>
  
  <pre class="lang-py prettyprint-override"><code>migrations.AddField(
              model_name='student',
              name='extend',
              field=models.IntegerField(blank=True, null=True),
          ),
  </code></pre>
  
  <p><strong>My Error is :</strong></p>
  
  <p><strong>How to queryset at migration file if column does not exist?</strong></p>