Create custom session handler in php using mysql database

class mySession implements SessionHandlerInterface {

    private  $dbConnection;
    private  $sessionLifeTime;

    function  __construct(){

        //set session handler
        session_set_save_handler(array(&$this,"open"),
            array(&$this,"close"),
            array(&$this,"read"),
            array(&$this,"write"),
            array(&$this,"destroy"),
            array(&$this,"gc"));
    }

    //function to create session
    function open($savePath,$sessionName){

        //get the db connection
        $this->dbConnection = new PDO('mysql:dbname=db_based_session;host:localhost', 'XXX', 'XXX');

//set the default session expiration time
$this->sessionLifeTime = get_cfg_var('session.gc_maxlifetime');

if ($this->dbConnection)
return true;
else
return false;
//if it was a file based then we have to create file for all session and have to store in specified path

}

function close()
{

//expire time for this session
$this->gc(get_cfg_var('session.gc_maxlifetime'));

//destroy db connection
$this->dbConnection = null;

}

function read($sessionId)
{

//read data
$query = "SELECT session_data FROM my_sessions WHERE session_id = :session_id AND session_expires > :session_expires";
$preparedQuery = $this->dbConnection->prepare($query);
$resultSet = $preparedQuery->execute(array(":session_id" => $sessionId, ":session_expires" => time()));
if ($resultSet)
return $resultSet->session_data;
else
return "";
}

function write($sessionId, $sessionData)
{

echo $sessionId;
//set expiration time
$newExpirationTime = time() + $this->sessionLifeTime;

//check if session is already there with specified id
$query = "SELECT * FROM my_sessions WHERE session_id = :session_id";
$preparedQuery = $this->dbConnection->prepare($query);
$preparedQuery->execute(array(":session_id" => $sessionId));
$output = $preparedQuery->fetch(PDO::FETCH_COLUMN, 0);

if ($output) {
$result = $output->fetch(PDO::FETCH_COLUMN, 0);
//yes there is session with specified id then increase then update the session expiration time
if ($result) {
$updateQuery = "UPDATE my_sessions SET session_expires = ?, session_data = ? WHERE session_id = ?";
$preparedQuery = $this->dbConnection->prepare($updateQuery);
$preparedQuery->execute(array($newExpirationTime, $sessionData, $sessionId));
if ($updateQuery)
return true;
else
return false;
}

}

//new session
$insertQuery = " INSERT INTO my_sessions (session_id,session_expires,session_data) VALUES(:session_id,:session_expires,:session_data)";
$preparedQuery = $this->dbConnection->prepare($insertQuery);

$result = $preparedQuery->execute(array(
":session_id" => $sessionId,
":session_expires" => $newExpirationTime,
":session_data" => $sessionData));

if ($result)
return true;

//at the end if there is any issue
return false;

}

//session destroy function

function  destroy($sessionId)
{
$deleteQuery = "DELETE FROM my_sessions WHERE session_id =?";
$deleteQueryResult = $this->dbConnection->prepare($deleteQuery);
$deleteQueryResult->execute(array($sessionId));
if ($deleteQueryResult)
return true;
else
return false;
}

function gc($sessMaxLifeTime)
{

$deleteQuery = "DELETE FROM my_sessions WHERE session_expires dbConnection->prepare($deleteQuery);
$result = $preparedQuery->execute(array(time()));
if ($result)
return true;
else
return false;
}

}

$session = new mySession();
session_start();
echo session_id();
$_SESSION['abc'] = "whats up";
$_SESSION['kk'] = "hello";

echo $_SESSION['kk'];

//session_destroy();