function to check if id exist - does not work?

[futurewebsites]

Hi I have written a function to see if an id in a given table exists but it doesn't work any ideas why?

 function doesExist($table,$where,$whereArray,$db)
 {
     $chk = $db->query("SELECT id FROM $table WHERE $where",$whereArray);
    if(count($chk)>0)
     {
         echo $chk['id']; exit();
         return $chk['id'];
     }
    else
    {
    return false;
     }
 }

It always returns false :( I pass the values to it like:
$table = "tablename";
$where = "field = :field";
$chkArray = ["field"=>"value"];
$chk = doesExist($table,$where,$chkArray,$db);

[YamilBracho]

I use this code :
public function exists($table, $where = NULL) {
$sql = "SELECT EXISTS(SELECT 1 FROM $table ";

    if (!is_null($where)) {
        $sql .= " WHERE $where ";
    }

    $sql .= ' LIMIT 1)';
    $row = $this->db->column($sql, null);
    return $row[0];
}

And to call

$found = exists('tablename', 'field = value');