Introduction Sessions PHP

A session is basically a way of storing variables and making them available across multiple pages on your web site. This can be very useful as the user does not ever need to see what is going on behind the scenes.

Here i will demonstrate a session in its simplest form, that is, setting a session variable on a web page and recalling the value of it on a second page. i will begin by creating a session variable standard example PHP called 'foo' and i shall assign the value of 'bar' to it.

i use the PHP super global $_SESSION to hold it. More on this later. my first page i will call example.php and the code see below.


?php
// begin the session
session_start(); 

// set the value of the session variable 'foo'
$_SESSION['foo']='bar'; 

// echo a little message to say it is done
echo 'Setting value of foo';

With that done, i can create session.php, this page will start a session, then it will echo the value of the session variable 'foo'. The code for session.php see below.


?php
// begin our session
session_start(); 

// echo the session variable
echo 'The value of foo is '.$_SESSION['foo'];

Try the above example, i will build on it as we go and discover new things to do with sessions.

How session work ?
Sessions can be used in two ways. The first is cookie based, and the second is url based. Most sessions are cookie based. What this means is that when a session is started, a cookie is set on the clients machine with a unique session ID or SID. The session variables are stored typically on a file on the server that matches the unique session ID. When a variable is required, the client or browser looks for the file matching the session ID and retrieves the corresponding variables from it. A typical session file stored in the default session file directory would look like this log_fd51ab4d1820aa6ea.

Now I'll show how to use the session to login to access can only be used by users who are logged in.
for the first I would call the index.php for login form the code see below.


?php
include('login.php'); // Includes Login Script
if(isset($_SESSION['login_user'])){
header("location: profile.php");
}

?>
<!DOCTYPE html>
<html>
<head>
<title>Login Form in PHP with Session</title>
<link href="style.css" rel="stylesheet" type="text/css">
</head>
<body>
<div id="main">
<h1>PHP Login Session Example</h1>
<div id="login">
<h2>Login Form</h2>
<form action="" method="post">
<label>UserName :</label>
<input id="name" name="username" placeholder="username" type="text">
<label>Password :</label>
<input id="password" name="password" placeholder="**********" type="password">
<input name="submit" type="submit" value=" Login ">
<span><?php echo $error; ?></span>
</form>
</div>
</div>
</body>
</html>

Now I will make login.php the code see below


?php
session_start(); // Starting Session
$error=''; // Variable To Store Error Message
if (isset($_POST['submit'])) {
if (empty($_POST['username']) || empty($_POST['password'])) {
$error = "Username or Password is invalid";
}
else
{
// Define $username and $password
$username=$_POST['username'];
$password=$_POST['password'];
// Establishing Connection with Server by passing server_name, user_id and password as a parameter
$connection = mysql_connect("localhost", "root", "");
// To protect MySQL injection for Security purpose
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysql_real_escape_string($username);
$password = mysql_real_escape_string($password);
// Selecting Database
$db = mysql_select_db("company", $connection);
// SQL query to fetch information of registerd users and finds user match.
$query = mysql_query("select * from login where password='$password' AND username='$username'", $connection);
$rows = mysql_num_rows($query);
if ($rows == 1) {
$_SESSION['login_user']=$username; // Initializing Session
header("location: profile.php"); // Redirecting To Other Page
} else {
$error = "Username or Password is invalid";
}
mysql_close($connection); // Closing Connection
}
}

after this. now create profile.php


?php
include('session.php');
?>
<!DOCTYPE html>
<html>
<head>
<title>Your Home Page</title>
<link href="style.css" rel="stylesheet" type="text/css">
</head>
<body>
<div id="profile">
<b id="welcome">Welcome : <i><?php echo $login_session; ?></i></b>
<b id="logout"><a href="logout.php">Log Out</a></b>
</div>
</body>
</html>

furthermore makes session.php to verify whether the user is available in the database the code see below


?php
// Establishing Connection with Server by passing server_name, user_id and password as a parameter
$connection = mysql_connect("localhost", "root", "");
// Selecting Database
$db = mysql_select_db("user", $connection);
session_start();// Starting Session
// Storing Session
$user_check=$_SESSION['login_user'];
// SQL Query To Fetch Complete Information Of User
$ses_sql=mysql_query("select username from login where username='$user_check'", $connection);
$row = mysql_fetch_assoc($ses_sql);
$login_session =$row['username'];
if(!isset($login_session)){
mysql_close($connection); // Closing Connection
header('Location: index.php'); // Redirecting To Home Page
}
?>

after all made do not forget to make logout.php to get out of the session code see below


?php
session_start();
if(session_destroy()) // Destroying All Sessions
{
header("Location: index.php"); // Redirecting To Home Page
}
?>

Now I am going to create a database and table in phpmyadmin


CREATE DATABASE user;
CREATE TABLE login(
id int(10) NOT NULL AUTO_INCREMENT,
username varchar(255) NOT NULL,
password varchar(255) NOT NULL,
PRIMARY KEY (id)
)

another one to decorate the login form makes style.css


@import http://fonts.googleapis.com/css?family=Raleway;
/*----------------------------------------------
CSS Settings For HTML Div ExactCenter
------------------------------------------------*/
#main {
width:960px;
margin:50px auto;
font-family:raleway
}
span {
color:red
}
h2 {
background-color:#FEFFED;
text-align:center;
border-radius:10px 10px 0 0;
margin:-10px -40px;
padding:15px
}
hr {
border:0;
border-bottom:1px solid #ccc;
margin:10px -40px;
margin-bottom:30px
}
#login {
width:300px;
float:left;
border-radius:10px;
font-family:raleway;
border:2px solid #ccc;
padding:10px 40px 25px;
margin-top:70px
}
input[type=text],input[type=password] {
width:99.5%;
padding:10px;
margin-top:8px;
border:1px solid #ccc;
padding-left:5px;
font-size:16px;
font-family:raleway
}
input[type=submit] {
width:100%;
background-color:#FFBC00;
color:#fff;
border:2px solid #FFCB00;
padding:10px;
font-size:20px;
cursor:pointer;
border-radius:5px;
margin-bottom:15px
}
#profile {
padding:50px;
border:1px dashed grey;
font-size:20px;
background-color:#DCE6F7
}
#logout {
float:right;
padding:5px;
border:dashed 1px gray
}
a {
text-decoration:none;
color:#6495ed
}
i {
color:#6495ed
}

after all finished trying to run apache, dont forget to save all files in one folder.
Hope you like it, keep reading our other blogs.