problem in a validation form - php - php

Question

i have a problem in my code. I have an ajax validation that calls a php file (where the data is validated).
The php returns echos like "invalidData" and in the javascript i check if (data=="invalidData") {//something}
The problem are the includes. Incredible thing.
<?php
include("includes/f_banco.php");
conecta ();
function get_post_var($var) {
$val = $_POST[$var];
if (get_magic_quotes_gpc())
$val = stripslashes($val);
return $val;
}
$name = get_post_var('name');
function validateName($name){
if(strlen($name) < 4 || (empty($name))) {
echo "invalidData";
return false;
}
else {
$name = mysql_real_escape_string($name);
$check = mysql_query("SELECT username FROM users WHERE username ='".$name."'")
or die(mysql_error());
$check2 = mysql_num_rows($check);
if ($check2 == 0 && $name != "") {
echo "validData";
return true;
} else {
echo "invalidData";
return false;
}
}
}
error_reporting(E_ALL);
validateName($name);
?>
in the code above i only can check if the name is empty if i don't put the includes in the file. If i put the result is again and again different than invalidData.
The connection to the database is not made too or if is made the return is not the correct. Important: the include file is correct, i test in another example and the database is correct too.
thanks
Edit: **LAST VERSION**
<?php
error_reporting(-1);
require 'includes/f_banco1.php';
$name = $_POST["carlos"];
function validateName($name){
if(strlen($name) < 4 || (empty($name))) {
echo "nomeInvalido";
return false;
}
else {
$name = mysql_real_escape_string($name);
$check = mysql_query("SELECT username FROM users WHERE username ='".$name."'")
or die(mysql_error());
$check2 = mysql_num_rows($check);
if ($check2 == 0 && $name != "") {
echo "nomeValido";
return true;
} else {
echo "nomeInvalido";
return false;
}
}
}
validateName($name);
echo "this must appear";
?>
output:
Notice: Undefined index: carlos in C:\Users\fel\VertrigoServ\www\login\validation.php on line 8
nomeInvalidothis must appear

Answer 1

Probably PHP debug 101... just do a
<?php
error_reporting(-1);
...
?>
And inspect the error...

Answer 2

Try updating your query to be the following:
SELECT `username` FROM users WHERE `username` ='".$name."'
And, another question... If you already know what the username is, then why are you running a query to find the username? I assume you're just checking to see if the username exists.