<?php
ob_start();
$host="localhost"; // Host name
$username="sj"; // Mysql username
$password="this r my password"; // Mysql password
$db_name="sj_xbl"; // Database name
$tbl_name="admins"; // 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");

// Define $sjadmin and $sjadminpass
$sjadmin=$_POST['sjadmin'];
$sjadminpass=$_POST['sjadminpass'];

// To protect MySQL injection (more detail about MySQL injection)
$sjadmin = mysql_real_escape_string($sjadmin);
$sjadminpass = mysql_real_escape_string($sjadminpass);

$sql="SELECT * FROM $tbl_name WHERE username='$sjadmin' and password='$sjadminpass'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $sjadmin and $sjadminpass, table row must be 1 row

if($count==1){
// Register $sjadmin, $sjadminpass and redirect to file "login_success.php"
session_start():
$_SESSION['uid'] = $uid;
$_SESSION['sjpass'] = $sjpass;
header("location:login_success.php");
}
else {
echo "Wrong Username or Password";
}

ob_end_flush();
?>