Test MySQL SELECT-UPDATE/INSERT overload

<?php
    global $DB;

    $code = rand(10, 100000);
    //$code = date("YmdHis");

    $data = array(
        'code' => $code,
        'data' => 'test data'
    );

    $count_insert = 0;
    $count_update = 0;

    for( $i=0; $i < 100; $i++ )
    {

        // Check of exists
        $q = $DB->query("SELECT * FROM `test_overload` WHERE `code`='{$code}'");
        if( $q->num_rows == 0 )
        {
            $DB->query($DB->insert_string('test_overload', $data));
            $count_insert++;
        }
        else
        {
            $DB->query($DB->update_string('test_overload', $data, array('id'=>$q->row['id'])));
            $count_update++;
        }
    }

    echo "<p>Inserts: $count_insert</p>";
    echo "<p>Updates: $count_update</p>";
?>