Doing $wpdb->get_results returns NULL, doing the same query in my DB returns correct value

Question

I have this query to do in my code:

  function get_item($id){
    global $wpdb;

    $post_id_query = "SELECT * FROM wp_postmeta WHERE post_id = ". $id ." AND meta_key LIKE '%main%'";
    $call_post_id_call = $wpdb->get_results($wpdb->prepare($post_id_query));

    return $call_post_id_call;
  }

  $main_item = get_item(34487);

If I run SELECT * FROM wp_postmeta WHERE post_id = 34487 AND meta_key LIKE '%main%' on my DB it works...

I'm not very keen on wordpress to be honest.

Answer 1

The following script will help you to identify if there any error exists in the query.

$wpdb -> show_errors ();
$call_post_id_call = $wpdb->get_results($wpdb->prepare($post_id_query));
$wpdb -> print_error ();