• HTTP is a State less protocol.
• Why maintaining state.
• Ways to maintain it over Web
• Session
• Cookie

• Session is the period of activity between a user logging in and logging out of a (multi-user) system.
  

•  Session is a semi-permanent interactive information interchange, also known as a dialogue, a conversation or a meeting, between two or more communicating devices, or between a computer and user.
  

• session_start() OR session_register() 
• The Global Var : $_SESSION
• Run time Configuration
• $ php -i | grep session
• Setting Session
• $_SESSION['user_id'] = 'SomeId';
• Un-setting Session
• unset($_SESSION['user_is']);
• DO NOT ==> unset($_SESSION); 

• Also known as HTTP cookie, web cookie, or browser cookie
• It is a small piece of data sent from a website and stored in a user's web browser.
  
• PHP transparently supports HTTP cookies.
  
• Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users.

• setcookie()
• Name
• Value
• Expire
• setrawcookie()
• The Global varriable : $_COOKIE
• Configuration 
• $ php -i | grep cookie

• mysql
• mysqli
• pgsql
• mongo

 # MySQL Connect & Close : Till 5  <?php       $mysqlObj = mysql_connect('localhost' , 'mysql_user' , 'password');      if(!$mysqlObj) {        die('[' . mysql_errorno() . ']Could not connect to the DB : ' .                  mysql_error());       }       mysql_close($mysqlObj); ?>
 # MySqli Connect & Close : > 5   <?php     $mysqli = new mysqli('localhost' , 'user' , 'password' , 'database');     if($mysqli->connect_errno) {     echo 'Failed to connect to Mysql : (' . $mysql->connect_errno . ' )' . $mysql->connect_error;     }?>

• Common interface to any number of database systems.
  
• Written in C, so you know it’s FAST!
• Designed to make use of all the PHP 5.1 features to simplify interface.

• Many native database extensions that are similar but do not provide the same interface.
  
• In most cases, very old code that does not even scratch the surface of what PHP can offer.
  
• In many instances does not account for all the capabilities offered by the database.
  

• MySQL 3,4,5 (depends on client libs)
  
• PostgreSQL
• SQLite 2 & 3
• ODBC
• DB2
• Oracle
• Firebird
• FreeTDS/Sybase/MSSQL

 // MySQL connection
  $db = new PDO(‘mysql:host=localhost;dbname=testdb’, $login, $passwd);

 // PostgreSQL
  $db = new PDO(‘pgsql:host=localhost port=5432 dbname=testdb user=john password=mypass’);

 // SQLite
  $db = new PDO(‘sqlite:/path/to/database_file’);
 // Handling Exceptions    <?php    try {
          $db = new PDO(…);
    } catch (PDOException $e) {
          echo $e->getMessage();
    }
    ?>

     <?php     //Passing an argument for creating Persistent Connection.     $opt = array(PDO::ATTR_PERSISTENT => TRUE) ;
     try {
         $db = new PDO(“dsn”, $l, $p, $opt);
     } catch (PDOException $e) {
         echo $e->getMessage();
     }     ?>

• Direct Execution
• Prepared Statement
• Compile once, execute as many times as you want.
• Clear separation between structure and input, which prevents SQL injection.
  
• Often faster then query()/exec() even for single runs
  

 # Insert  <?php   $title = 'PHP Securities';   $author = "Rasmus Leodorf";   $sql = "INSERT INTO books (title,author) VALUES (:title,:author)";   $q = $db->prepare($sql);   $q->execute(array(':author' => $author , ':title' => $title));   ?>
  # Update  <?php   $title = 'PHP Pattern'; $author = 'Someone'; $id = 3;   $query = 'UPDATE books SET title=? , author=? WHERE id=?';   $q = $db->prepare($sql);   $q->execute(array($title , $author , $id));   ?>