的mysql_query（“回滚”）; 不起作用

This code do a transaction with all queries stored in $in. for example $in = "Query1; Query2; Query3;"

When one of them fails, it is rolled back but has no effect and the queries that had no errors are inserted into the database

    $conn = mysql_connect($dbhost, $dbuser, $dbpass);
    if(! $conn )
    {
      die('ERR');
    }

    mysql_select_db('db445123652');

    mysql_query("START TRANSACTION");


    $strlen = strlen( $in);

    $ini = 0;

    for( $i = 0; $i <= $strlen; $i++ ) {
        $char = substr( $in, $i, 1 );

        if($char == ';' )
        {

            $resul = mysql_query(substr( $in, $ini, $i ));


            if(!$resul)
            {                   
                echo  mysql_error();
                mysql_query("ROLLBACK"); 
                echo 'Rollback';
                break;

            }
            else{

            $ini = $i + 1;

            }


        }

    }


    if($i==($strlen+1) && $resul)
    {
        echo 'OK';
        mysql_query("COMMIT");

    }

The database is in a 1&1 host and I acces through phpmyadmin.

check for your database to table engine, if it is set to InnoDb or not.
there is difference between MyISAM and Innodb refer http://www.rackspace.com/knowledge_center/article/mysql-engines-myisam-vs-innodb