title: SELECT query return error on Empty result
body: <p>I'm using <code>SELECT</code> query as a subquery in Query given below...</p>
  
  <pre><code>SELECT COUNT (`Notification`.`id`) AS `count`
  FROM `listaren_mercury_live`.`notifications` AS `Notification`
  WHERE NOT FIND_IN_SET(`Notification`.`id`,(SELECT read_ids FROM read_notifications WHERE user_id = 46))
  AND((notisfication_for IN("all","India"))
  OR(FIND_IN_SET(46,notification_for))
  </code></pre>
  
  <p>This query working fine when</p>
  
  <pre><code>SELECT read_ids FROM read_notifications WHERE user_id = userid)
  </code></pre>
  
  <p>return result like 21,22,23,24</p>
  
  <p>but when this query return empty. </p>
  
  <p>The result id <code>0</code> instead of <code>3</code>. There are 3 unread notifications for the user; so the result must be <code>3</code></p>
  
  <p><strong>Problem</strong></p>
  
  <p>The query gives correct result when internal select query's return like</p>
  
  <pre><code>12,42 
  </code></pre>
  
  <p>but if query return null then the whole query's result becomes 0.</p>
  
  <p><strong>Expected Result With Query</strong></p>
  
  <p><a href="https://i.stack.imgur.com/XrVE9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XrVE9.png" alt="Expected Result"></a></p>
  
  <p><strong>Result I'm getting</strong></p>
  
  <p><a href="https://i.stack.imgur.com/TCI2H.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TCI2H.png" alt="Result I&#39;m getting"></a></p>
  
  <p>I just want if the subquery returns an empty value. Then the query <strong>(Notification.id,(SELECT read_ids FROM read_notifications WHERE user_id) = 46)</strong> result looks like</p>
  
  <pre><code> (`Notification`.`id`,(0))
  </code></pre>
  
  <p>instead of</p>
  
  <pre><code>(`Notification`.`id`,())
  </code></pre>
  
  <p>So it will work properly</p>
  
  <p>Please tell me what improvement I need in this.</p>
  
  <p>Thanks</p>