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There are times when it is necessary (and good practice) to terminate a session and destroy all data associated with the current session. The function session_destroy is responsible for handling the described actions; however, this function is limited in its ability by not unsetting (or clearing) the global variables tied to the session or the respective cookies. This requires a more detailed approach: <?php session_start(); // Unset all session variables $_SESSION = array(); // Unset all cookie variables if(isset($_COOKIE[session_name()])){ setcookie(session_name(),'', time()-48000,'/'); } ?>

PHP stores all the session data associated with a session ID in a single string and handles the decoding of this string automatically. However, there are times when it may be necessary or beneficial to handle this process manually. The first thing to understand is how the string is put together. In the following example, three session variables are stored (last name, first name and phone number): lname|s:6:"Gordon";fname|s:6:"Jethro";phone|s:10:"7197235674"; The session variables are separated by a semicolon (;) and then can be broken down into their individual components: name of the variable, length of the string that is contained and the value itself. For the session variable lname, the length of the string is 6 characters long and the value that is stored in the string is "Gordon". Encoding the Session Variables The function session_encode allows for all the session variables available to the user to be encoded into a single

Once the session data has been stored, retrieving (or recalling) this information is also very easy to setup. The following demonstrates how this is accomplished: <?php print "Dear ".$_SESSION['fname']." ".$_SESSION['lname'].","; ?>

Once the session has been initialized, the data that must remain persistently can be stored in the superglobal $_SESSION array. The following are examples of storing persistence data to this superglobal array: <?php $_SESSION['fname'] = 'George'; $_SESSION['lname'] = 'Burnes'; ?>

As stated earlier, the process of PHP maintaining information from one session to the next for a visitor is pretty straight forward without lacking in capability. This maintaining of information (getting to know the end user) is accomplished through session handling tasks. Starting a Session It is necessary to tell PHP when to open up its eyes and prepare for the possibility of having to get to know an end user. This process is accomplished through the function session_start(). This function initializes the session data or continues the current session that is being passed by a request, such as a GET, POST or a cookie. <?php session_start(); ?> Setting up the Session "Key" After starting the session process, it is important to identify the "key" by which the user will be remembered. This key is stored on the end users machine and is called when interacting with the end user machine with the same function; session_id(). <?php session_s

What is Session Handling Hyper Text Transfer Protocol (HTTP) is the method on which information is transferred from a server to a client on the world wide web. This protocol is static in nature, that is every request is a new request and no persistence (or memory of a previous transfer) remains within the protocol itself. This has its advantages in the form of safety, the requests by either the client or the server has no long term affects on the other. This provides a level of security that could be related to a friendly acquaintance with each other and no long term affects are felt by the interaction. However, for the application developer (and dare it be said, also for the end user), there are times when a more intimate relationship is needed to add value to the experience. This is where session handling comes in. Basically, when a user interacts with a web page, the application attempts to get to know the person and retain a memory of their visit. Maintaining State I

Even though developers (most at least) strive for an application free of bugs, no application (except minor projects) can be expected to be completely bug-free. For that purpose, a good practice for programmers is to build in code that will trap and display errors in a way that is both meaningful and useful to assist in the correction of the error. PHP offers two functions that can display error messages from MySQL: • mysql_error() - This function displays the error message (if there was one) from the last MySQL function. The language that the message will be displayed in is based on the target language that is setup in the MySQL server. However, even if a fluent speaker of the message language were to read the majority of error messages returned, they would most likely still have a difficult time understanding what was said. Needless to say, error messages from MySQL are not very verbose or informative. <?php // Load variables used in mysql_connect and connect to serv