PHP Ajax Login Validation Tutorial

Create  design for table name contact.

CREATE TABLE IF NOT EXISTS `username` (

  `id` int(11) NOT NULL AUTO_INCREMENT,

  `username` varchar(50) NOT NULL

  `password` varchar(50) NOT NULL,

   PRIMARY KEY (`id`)

)

 Contains database connectivity code

$hostname = "Host name";

$user = "UserName";

$password = "Password";

$database = "Database Name";

$con = mysql_connect($hostname, $user,

       $password or die("Could not connect database");

//Create a new connection

mysql_select_db($database, $con) or

                 die("Could not select database");

Contains login form and ajax code

<script type="text/javascript">

    function validLogin(){

       var uname=$('#username').val();

       var password=$('#password').val();

       var dataString = 'username='+ username + '&password='+ password;

       $("#flash").show();

       $("#flash").fadeIn(400).html('<img src="image/loading.gif" />');

       $.ajax({

             type: "POST",

             url: "processed.php",

             data: dataString,

             cache: false,

             success: function(result){

             var result=trim(result);

             $("#flash").hide();

             if(result=='correct'){

                  window.location='index.php';

             }else{

                  $("#errorMessage").html(result);

             }

        }

  });

}

function trim(str){

var str=str.replace(/^\s+|\s+$/,'');

return str;

}

</script>

processed.php

Contains login logic  and validation code.

<?php

session_start();

include_once('inc/dbConnect.inc.php');

$message=array();

if(isset($_POST['username']) && !empty($_POST['username'])){

     $username=mysql_real_escape_string($_POST['username']);

}else{ 

     $message[]='Please enter username';

}

if(isset($_POST['password']) && !empty($_POST['password'])){

     $password=mysql_real_escape_string($_POST['password']);

}else{

     $message[]='Please enter password';

}

$countError=count($message);

if($countError > 0){

     for($i=0;$i<$countError;$i++){

         echo ucwords($message[$i]).'<br/><br/>';

     }

}else{

     $query="select * from user where username='$username' and

             password='$password'";

     $res=mysql_query($query);

     $checkUser=mysql_num_rows($res);

     if($checkUser > 0){

         $_SESSION['LOGIN_STATUS']=true;

         $_SESSION['UNAME']=$username;

         echo 'correct';

    }else{

         echo ucwords('please enter correct user details');

    }

}

?>

index.php

<?php

 session_start();

 if(!isset($_SESSION['LOGIN_STATUS'])){

      header('location:login.php');

 }

?>

logout.php

Contains session destroy code.

<?php session_start(); session_destroy(); header('location:login.php'); ?>