con este codigo me marca error
Cita: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0' at line 1
Cita:
Iniciado por carlosdanielmou 
Bueno, a ver si te puedo ayudar:
Código PHP:
<?php
//entramos a la base de datos
$conexion = mysql_connect("localhost", "xxxxxx", "xxxxxxx");
mysql_select_db("xxxxxxxxxx", $conexion);
$queEmp = "SELECT * FROM registro_usuarios WHERE username = '"+$_GET['s_username']+"' ORDER BY username";
$resEmp = mysql_query($queEmp, $conexion) or die(mysql_error());
$totEmp = mysql_num_rows($resEmp);
?>