function get_create_mb_id($length) {

    $characters  = '0123456789';

    $characters .= 'abcdefghijklmnopqrstuvwxyz';

    $characters .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

    $string_generated = '';

    $nmr_loops = $length;

    while ($nmr_loops--) {

        $string_generated .= $characters[mt_rand(0, strlen($characters) - 1)];

    }

    return $string_generated;

}

$j = 0;

do {

    $mb_id = get_create_mb_id(10);

    $sql3 = " select count(*) as cnt from {$g5['member_table']} where mb_id = '".$mb_id."' ";

    $row3 = sql_fetch($sql3);

    if(!$row3['cnt'])

        break;

    else {

        if($j > 20)

            die('Member ID Error');

    }

} while(1);

echo $mb_id;