Using Sessions in PHP - UK Web Hosting | Dedicated Server Windows and Linux VPS Forum

**Ben** · #1 (**permalink**) 23-06-2008, 20:02

Sessions and cookies are a type of way for people to stay "logged in" on any PHP-enabled web site hosting efficently without having to re-login every time they close the browser or even refresh the page. Cookies are pretty more up to date than sessions but are a little more complicated to use; but of course very easy to learn. In this tutorial, however I will be covering sessions - to an extent they're better than cookies because they only stay there until the user closes the browser and after, they'll need to re-login but cookies would stay on the user's computer until they clear their cookies from the browser's Tools menu.

I presume you already are familar with PHP syntax, etc so let's get straight down to the function that starts a session in PHP:

PHP Code:


			
<?php
session_start();
?>
<html>
<head>
<title>PHP Sessions</title>
</head>
<body>

</body>
</html>

Now basically here the session_start() function is to start a session in PHP and is always required generally before anything else on a Web page, or to be more precise - before anything that outputs (like header() function, etc).

Now, create an HTML form like so:

Code:

<form action="index.php">
<input type="text" name="message">
</form>

Just for convenience for people who are not familar with XHTML I won't be putting extra code that is required for XHTML validity just incase you aren't familar with it. Now, on the same index.php file, just below that HTML code, paste this chunk of PHP code:

PHP Code:


			
<?php
$_SESSION['Session'] = $_POST['message'];
echo $_SESSION['Session'];
?>

And this will display the text they entered in the form persistently regardless how many times the user refreshes as the message has been saved into a session - so until they close their browser, that will be displayed on the page - and that's one form of a dynamic Web page!

So, for reference these are the things you'll generally need for sessions:

$_SESSION['SessionName'] = value;
session_start();

Now the value in the session variable could be the user's logged in username or if you're making an e-commerce application - the item ID the person wanted to save to come back to - but for e-commerce hosting apps in this case, cookies may be more convenient just in-case the user closes their browser. But in most cases sessions would be best as they're more convenient for safety especially for people who use shared computers, etc. But, using either sessions or cookies is entirely up to you. You can get more information on cookies in PHP at php.net/cookies and sessions at php.net/sessions.

Remember references of the massive array of functions in PHP are available at www.php.net/function_name and PHP is available with hosting at eUKhost

.

Rock · #2 (**permalink**) 24-06-2008, 07:33

Hi Ben, another useful tutorial..

I'm sure this is going to be beneficial for others too.. as usual.. keep up the good work...

**eUK-Martin** · #3 (**permalink**) 24-06-2008, 10:41

Hello,

Great one Ben..

I would like to add that if you are running PHP on Windows then sessions will expire if the application pool refreshes. The default idle time for a pool to get refreshed is 10 minutes. This can be easily edited from the properties of Application Pool in IIS Web Server.

**DavidAllen** · #4 (**permalink**) 25-06-2008, 13:32

Good tutorial. I would also like to add that the session data can be stored in a database, thus avoiding any problems with application pools (winows) or other possible security risks in a shared hosting environment

just create a session class

PHP Code:


			
class session

{

    /* Define the MySQL Server table you wish to use with

       this class, this table MUST exist. */

    var $ses_table = "YourTableName";



    /* Change to 'Y' if you want to connect to a db in

       the _open function */

    var $db_con = "Y";



    /* Configure the info to connect to MySQL, only required

       if $db_con is set to 'Y' */

    var $db_host = "localhost";

    var $db_user = "username";

    var $db_pass = "password";

    var $db_dbase = "database_name";



    /* Create a connection to a database */

    function db_connects() {

        $mysql_connect = @mysql_connect ($this->db_host,

                                          $this->db_user,

                                          $this->db_pass);

        $mysql_db = @mysql_select_db ($this->db_dbase);



        if (!$mysql_connect || !$mysql_db) {

            return FALSE;

        } else {

            return TRUE;

        }

    }



    /* Open session, if you have your own db connection

       code, put it in here! */

    function _open($path, $name) {

        if ($this->db_con == "Y") {

            $this->db_connects();

        }



        return TRUE;

    }



    /* Close session */

    function _close() {

        /* This is used for a manual call of the

           session gc function */

        $this->_gc(0);

        return TRUE;

    }



    /* Read session data from database */

    function _read($ses_id) {

        $this->db_connects();

        $session_sql = "SELECT * FROM " . $this->ses_table

                     . " WHERE ses_id = '$ses_id'";

        $session_res = mysql_query($session_sql);

        if (!$session_res) {

            return '';

        }



        $session_num = mysql_num_rows ($session_res);

        if ($session_num > 0) {

            $session_row = mysql_fetch_assoc ($session_res);

            $ses_data = $session_row["ses_value"];

            return $ses_data;

        } else {

            return '';

        }

    }



    /* Write new data to database */

    function _write($ses_id, $data) {

        $this->db_connects();

        $session_sql = "UPDATE " . $this->ses_table

                     . " SET ses_time='" . time()

                     . "', ses_value='".addslashes($data)."' WHERE ses_id='$ses_id'";

        $session_res = mysql_query ($session_sql) or die('Query failed: ' . mysql_error().'<br>'.$session_sql);

        if (!$session_res) {

            return FALSE;

        }

        if (mysql_affected_rows ()) {

            return TRUE;

        }



        $session_sql = "INSERT INTO " . $this->ses_table

                     . " (ses_id, ses_time, ses_start, ses_value)"

                     . " VALUES ('$ses_id', '" . time()

                     . "', '" . time() . "', '$data')";

        $session_res = mysql_query ($session_sql);

        if (!$session_res) {

            return FALSE;

        }         else {

            return TRUE;

        }

    }



    /* Destroy session record in database */

    function _destroy($ses_id) {

        $this->db_connects();

        $session_sql = "DELETE FROM " . $this->ses_table

                     . " WHERE ses_id = '$ses_id'";

        $session_res = mysql_query ($session_sql);

        if (!$session_res) {

            return FALSE;

        }         else {

            return TRUE;

        }

    }



    /* Garbage collection, deletes old sessions */

    function _gc($life) {

        $this->db_connects();

        $ses_life = strtotime("-2 hours");



        $session_sql = "DELETE FROM " . $this->ses_table

                     . " WHERE ses_time < $ses_life";

        $session_res = mysql_query ($session_sql);





        if (!$session_res) {

            return FALSE;

        }         else {

            return TRUE;

        }

    }

}

Then when you want to start the session just add a few lines to the tutorial above

PHP Code:


			
require("classes/session.class.php"); //the file with the above class code in



/* Create new object of class */

$ses_class = new session();



/* Change the save_handler to use the class functions */

session_set_save_handler (array(&$ses_class, '_open'),

                          array(&$ses_class, '_close'),

                          array(&$ses_class, '_read'),

                          array(&$ses_class, '_write'),

                          array(&$ses_class, '_destroy'),

                          array(&$ses_class, '_gc'));

/* Start the session */

session_start();

That's it - session data stored safely in a database - with the advantage that you can query it to find out things like - who's online

**eUK-Martin** · #5 (**permalink**) 25-06-2008, 20:33

Awesome David..
I really admire your command on PHP... Great job.

~~aliyassa~~ · #6 (**permalink**) 05-08-2008, 12:03

Building web applications with membership management is one of the most frequent tasks that every programmer does. Managing membership data, such as username, password and the member's profile with sessions in PHP is the easiest and simplest solution, although it is not the only one.