How to choose page using if else in mysql_num_rows - php

Question

Please help me I want my program to choose a site if it has not yet username then it will proceed it to ch_uname.php. Then if the login credentials have already username then it will be preceded to index_profile.php. Thank you in advance.
if(mysql_num_rows($runcreds)> 0 ) //checking log in forms
{
if(mysql_num_rows($run_uname)>=1 ) //if username has already avalaible(proceed)
{
$_SESSION['Email_add']=$email;
echo "<script>window.open('modules/index_profile.php','_self')</script>";
}
if(mysql_num_rows($run_uname)<1)//choouse username if has not yet username
{
$_SESSION['Email_add']=$email;
echo "<script>window.open('forms/ch_uname.php','_self')</script>";
//modules/index_profile.php
}
}
else
{
echo "<script>alert('Admin details are incorrect!')</script>";
}
}

Answer 1

Here is a basic demonstration (using a PDO connection) of what I think you are looking for? I am assuming some stuff here because you don't give enough info before your code snippet:
session_start();
// I will use PDO because I cannot bring myself to use mysql_ in this demonstration
// Initiate connection (assigning credentials assumed)
$con = new PDO("mysql:host=$mysqlDB;dbname=$mysqlTable", $mysqlUser, $mysqlPass, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_SILENT));
if(isset($_POST['login'])) {
$username = trim($_POST['username']);
// Stop if empty
if(empty($username)) {
// You can echo or assign to a variable to echo down the page
echo 'Username cannot be empty';
return;
}
// Set up prepared statement
$query = $con->prepare("select Email_add,password from `users` where username = :username");
$query->execute(array(":username"=>$username));
// Loop through returned
while($row = $query->fetch(PDO::FETCH_ASSOC)) {
$result[] = $row;
}
// If the loop comes up blank, assign false (0)
$result = (isset($result) && !empty($result))? $result:0;
// If username exists
if($result != 0) {
// I am assuming you have some form of super secure hash method for passwords...
$password = bcrypt($_POST['password']);
// If passwords match, create session
if($result[0]['password'] == $password) {
$_SESSION['Email_add'] = $result[0]['Email_add'];
// You probably don't need javascript to redirect
header('Location: modules/index_profile.php');
exit;
}
else {
// Password doesn't match
// You can echo or assign to a variable to echo down the page
echo 'Invalid Username/Password';
}
}
// This would mean the username doesn't exist
else {
header('Location: forms/ch_uname.php');
exit;
}
}