PHP echo ID after register on mysql database

Question

Hello guys I have this php code to register building data in a game that I'm developing. This code work fine.

What I like to know is how can I echo the auto increased ID of the object that I registered using this code when the register function successful.

<?php


$db = "database";//Your database name
$dbu = "username";//Your database username
$dbp = "password";//Your database users' password
$host = "localhost";//MySQL server - usually localhost

$dblink = mysql_connect($host,$dbu,$dbp);
$seldb = mysql_select_db($db);

if(isset($_GET['oid']) ){

     //Lightly sanitize the GET's to prevent SQL injections and possible XSS attacks
     $name = strip_tags(mysql_real_escape_string($_GET['oid']));
     $sql = mysql_query("INSERT INTO `$db`.`building` (`id`,`oid`) VALUES ('','$oid');");

     if($sql){

          //The query returned true echo the newly registered id
          echo '????'; 

     }else{

          //The query returned false - you might want to put some sort of error reporting here. Even logging the error to a text file is fine.
          echo 'Fail to save data';

     }

}else{
     echo 'Fail-No object owner ID';
}

mysql_close($dblink);//Close off the MySQL connection to save resources.
?>

Please help me.

Answer 1

Use mysql_insert_id()

if($sql){

          //The query returned true echo the newly registered id
          echo mysql_insert_id($dblink); 

     }else{

          //The query returned false - you might want to put some sort of error reporting here. Even logging the error to a text file is fine.
          echo 'Fail to save data';

     }

Notes:

Here is reasoning of why you should not use Mysql but mysqli extension for php MySQL vs MySQLi when using PHP

From PHP developers:

It is recommended to use either the mysqli or PDO_MySQL extensions. It is not recommended to use the old mysql extension for new development. A detailed feature comparison matrix is provided below. The overall performance of all three extensions is considered to be about the same. Although the performance of the extension contributes only a fraction of the total run time of a PHP web request. Often, the impact is as low as 0.1%.