//login.php

<?php
include("db.php");
session_start();
if($_SERVER["REQUEST_METHOD"] == "POST")
{
$username=mysqli_real_escape_string($db,$_POST['username']);
$password=mysqli_real_escape_string($db,$_POST['password']);
$password=md5($password); // Encrypted Password
$sql="SELECT id FROM admin WHERE username='$username' and passcode='$password'";
$result=mysqli_query($db,$sql);
$count=mysqli_num_rows($db,$result);

if($count==1)
{
header("location: welcome.php");
}
else
{
$error="Your Login Name or Password is invalid";
}
}
?>
<form action="login.php" method="post">
<label>UserName :</label>
<input type="text" name="username"/><br />
<label>Password :</label>
<input type="password" name="password"/><br/>
<input type="submit" value=" Login "/><br />
</form>