title: PHP Clone the row from database but NULL is getting empty result
body: <p>I am trying to make a facebook style share post system using php and mysql. </p>
  
  <p>I want to clone the following screenshot row from data:
  <a href="https://prnt.sc/hhp97n" rel="nofollow noreferrer">https://prnt.sc/hhp97n</a></p>
  
  <p><a href="https://i.stack.imgur.com/z56xR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z56xR.png" alt="enter image description here"></a></p>
  
  <p>In this row you can see <code>post_hashtags</code> is <em><code>NULL</code></em> that means that post not have hashtag.
  When i share this post i am getting this screenshot: <a href="https://prnt.sc/hhp8rx" rel="nofollow noreferrer">https://prnt.sc/hhp8rx</a></p>
  
  <p><a href="https://i.stack.imgur.com/wjXVl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wjXVl.png" alt="enter image description here"></a></p>
  
  <p>I am not getting <em><code>NULL</code></em> for <code>post_hashtags</code> after the clone row. </p>
  
  <p>It should be like this after the clone row: <a href="https://image.prntscr.com/image/Z5nloIeBSta6KCDCQfinqA.png" rel="nofollow noreferrer">https://image.prntscr.com/image/Z5nloIeBSta6KCDCQfinqA.png</a></p>
  
  <p><a href="https://i.stack.imgur.com/SLMpH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SLMpH.png" alt="enter image description here"></a></p>
  
  <p>I'm not sure the way I'm going is true, but it works. I tried this with the following codes.</p>
  
  <pre><code>$query = mysqli_query($this-&gt;db,
    "SELECT post_id, post_text, post_title 
     FROM posts 
     WHERE post_id = '$post_id'") 
    or die(mysqli_error($this-&gt;db));
  $data=mysqli_fetch_array($query, MYSQLI_ASSOC); 
  
  $post_title = isset($data['post_title']) ? $data['post_title'] : NULL; 
  $post_text = isset($data['post_text']) ? $data['post_text'] : NULL; 
  $post_hashtags = isset($data['post_hashtags']) ? $data['post_hashtags'] : NULL; 
  
  $CloneThePost = mysqli_query($this-&gt;db,
    "INSERT INTO `posts`(post_title,post_text,post_hashtags)
     VALUES('$post_title','$post_text','$post_hashtags')"
    ) or die(mysqli_error($this-&gt;db));
  </code></pre>