query.php

<?
$tipo = $_GET['T'];
$valor = $_GET['V'];


$db = mysql_connect("smon.com.ar:3306","---","*******");
mysql_select_db("smon",$db);

switch ($tipo){
    case 0:
            $query = mysql_query("SELECT * FROM Users WHERE Uname = '" . $valor . "';",$db);
            break;
    case 1:
            $query = mysql_query("SELECT * FROM Users WHERE Mail = '" . $valor . "';",$db);
            break;
    case 2:
            $query = mysql_query("SELECT Preg FROM Users WHERE Uname = '" . $valor . "';", $db);
            $row = mysql_fetch_row($query);
            mysql_close($db);
            echo $row[0];
            return;
            break;
}


if (mysql_num_rows($query)!=0){
    echo "0";  //El dato existe en la base de datos
} else {
    echo "1";
}
mysql_close($db);

?>