first off, you cannot put session_start() at the top of a login page, because there is no session yet. I would just take out $_SERVER["REQUEST_METHOD"] == "POST") unless you know that the variables are being posted. Try this because i have a feeling you got this from another website.. Also, you dont need to make a session variable on the login screen because you are already going to register the username. If you want to register more variables, then add them to the to session_register.
session_register("myusername");
session_register("mypassword");
// Dont Need
$_SESSION['login_user']=$myusername;<?php
$host="localhost"; // Host name
$username=""; // Mysql username
$password=""; // Mysql password
$db_name="test"; // Database name
$tbl_name="members"; // Table name
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// username and password sent from form
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];
// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);
// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword");
session_register("active");
header("location:login_success.php");
}
else {
echo "Wrong Username or Password";
}
?>
