错误“警告：mysql_result（）[function.mysql-result]：无法跳转到第0行”

This is my error:

Warning: mysql_result() [function.mysql-result]: Unable to jump to row 0 on MySQL result index 53 in C:\xampp\htdocs\includes\class.rooms.php on line 35

This is the line in the coding:

return mysql_result(
       dbquery(
           "SELECT " . $var . " FROM rooms WHERE id = '" . $roomId . "' LIMIT 1"
       ), 0);

Firstly, function dbquery is unfamiliar to me. I know mysql_query, but maybe it's your own method. The problem is, most possibly, that your query returns no rows. Try debugging with

$result = ..query..
if (!mysql_num_rows($result))
    echo "No rows.";

Assuming that $var and $roomId are correctly populated , it might he useful to test your code excluding the dbquery function which seems to be a user defined function :

$query_temp = "SELECT " .$var ." FROM rooms WHERE id = '" .$roomId ."' LIMIT 1";

/*
 * This is for test purpose and in production you would not want to display neither the query nor error to the user.
 */

$result_temp = mysql_query( $query_temp ) or die ("Error in query: $query_temp. " .mysql_error( ) );

//  var_dump( mysql_fetch_array ( $result_temp ) );

return( $result_temp );

As already commented by shmuli it is worth to switch to mysqli or pdo in the beginning itself