sql error return json to jquery

i have ajax call that send data to the pph script which inserts it into database.

If for some reasons I have error when connecting to database ot error on insertion how do i sent some sort of error to ajax.

  <?php
  error_reporting(0);
   
   $a = $_POST['user'];
   $b = $_POST['name'];
   $c = $_POST['comment'];
   
   
   $link = mysql_connect('localhost', 'rot', 'joker1');
  
  if (!$link) {
       $arr = array('connect' => 0);
       //die('Could not connect: ' . mysql_error());
  }
  
 
  
  header('Content-type: application/json');
  echo json_encode($arr);
  
  
 ?>

This is the only way i was able to pass json back to ajax. Can anyone suggest better way to do this. I would like to keep die statement but in order to get it working i had to comment it off