使用MySQL存储会话数据

为了把会话数据存入数据库，需要先创建一个数据表。

    CREATE TABLE sessions
    (
      id varchar(32) NOT NULL,
      access int(10) unsigned,
      data text,
      PRIMARY KEY (id)
    );

session_set_save_handler('_open', '_close', '_read', '_write','_destroy','_clean');
function _open()
{
   global $_sess_db;

   $db_user = $_SERVER['DB_USER'];
   $db_pass = $_SERVER['DB_PASS'];
   $db_host = 'localhost';

   if ($_sess_db = mysql_connect($db_host, $db_user, $db_pass))
   {
     return mysql_select_db('lyw', $_sess_db);
   }

   return FALSE;
}

function _close()
{
  global $_sess_db;

  return mysql_close($_sess_db);
}

function _read($id)
{
   global $_sess_db;

   $id = mysql_real_escape_string($id);

   $sql = "SELECT data FROM sessions WHERE id = '$id'";

   if ($result = mysql_query($sql, $_sess_db))
   {
      if (mysql_num_rows($result))
      {
          $record = mysql_fetch_assoc($result);

          return $record['data'];
      }
   }

   return '';
 }

    function _write($id, $data)
    {
      global $_sess_db;

      $access = time();

      $id = mysql_real_escape_string($id);
      $access = mysql_real_escape_string($access);
      $data = mysql_real_escape_string($data);

      $sql = "REPLACE INTO  sessions VALUES  ('$id', '$access', '$data')";

      return mysql_query($sql, $_sess_db);
    }

    function _destroy($id)
    {
      global $_sess_db;

      $id = mysql_real_escape_string($id);

      $sql = "DELETE FROM sessions WHERE id = '$id'";

      return mysql_query($sql, $_sess_db);
    }

    function _clean($max)
    {
      global $_sess_db;

      $old = time() - $max;
      $old = mysql_real_escape_string($old);

      $sql = "DELETE FROM sessions WHERE access < '$old'";

      return mysql_query($sql, $_sess_db);
    }
session_start();
echo "Hello world!";
$_SESSION['name'] = "liuyiwei";
$_SESSION['desc'] = "This is only a test of session storage!";

?>