In PHP I don’t get the result I have in PHPmyAdmin [duplicate]

I am trying to use MySQL CONCAT_WS in a PDO Prepared Statement. I tested the query inside of phpMyAdmin and it works perfectly but not in a PDO Prepared Statement.

Here is the phpMyAdmin query which gives me the result i am looking for.

SELECT CONCAT_WS(',', `forum_tags`) AS ftags FROM `forum_topics` WHERE `forum_id` > 0

And the result i am looking for

phpMyAdmin result

I am having difficulty replacating that in my PDO Prepared Statement. Here is my current PDO code

  $zero = 0;
    
  $sql = "SELECT CONCAT_WS(',', `forum_tags`) AS ftags FROM `forum_topics` WHERE `forum_id` > :z;";
  
  $stmt = $this->pdo->prepare($sql);
   
  $stmt->execute([
                  ':z' => $zero
                 ]);  
       
  $results = $stmt->fetch(); //also tried fetchAll() as a test
  
  if(is_array($results))
  {
      
    return $results;  
      
  }//close if is array
      
    
  return false; 

What is the proper to way perform this with PDO Prepared Statement?

Thank you.