title: how can i delete child values while deleting parent value?
body: <p>i have one table questions where in i am adding question with parent_id = 0 are the parent question and question with parent_id (the parent_id will be same as the id of parent question) are called child question.</p>
  
  <p>this is my table.</p>
  
  <pre><code>id   parent_id   question
  1      0         what is computer ?
  2      1         Device
  3      1         Machine
  </code></pre>
  
  <p>i have tried this but no success.</p>
  
  <pre><code>DELETE FROM questions WHERE id = 1
  AND parent_id = id
  </code></pre>
  
  <p>how can i delete parent question along with its child question? </p>