/**
 * PHP中将session保存到数据库的代码
 *
 * @param 
 * @arrange 512-笔记网： 512Pic.com
 **/
// 'sessions' table schema
// create table sessions (
//   session_id char(32) not null,//   session_data text not null,//   session_expiration int(11) unsigned not null,//   primary key (session_id));
//
include_once 'DB.PHP';
// Global Variables
$dbh = NULL;
function on_session_start ($save_path,$session_name) {
	global $dbh;
	$dbh = DB::connect('MysqL://user:secret@localhost/SITE_SESSIONS',true);
	if (DB::isError($dbh)) {
		die(sprintf('Error [%d]: %s',$dbh->getCode(),$dbh->getMessage()));
	}
}
function on_session_end ()
{
   // Nothing needs to be done in this function
   // since we used persistent connection.
}
function on_session_read ($key)
{
	global $dbh;
	$stmt = "select session_data from sessions";
	$stmt .= " where session_id = '$key'";
	$stmt .= " and session_expiration > now()";
	$sth = $dbh->query($sth);
	$row = $sth->fetchRow(DB_FETCHMODE_ASSOC);
	return $row['session_data'];
}
function on_session_write ($key,$val)
{
	global $dbh;
	$val = addslashes($val);
	$insert_stmt = "insert into sessions values('$key','$val',now() + 3600)";
	$update_stmt = "update sessions set session_data = '$val',";
	$update_stmt .= "session_expiration = now() + 3600 ";
	$update_stmt .= "where session_id = '$key'";
	// First we try to insert,if that doesn't succeed,it means
	// session is already in the table and we try to update
	if (DB::isError($dbh->query($insert_stmt)))
		$dbh->query($update_stmt);
}
function on_session_destroy ($key)
{
	global $dbh;
   $stmt = "delete from sessions where session_id = '$key'";
   $dbh->query($stmt);
}
function on_session_gc ($max_lifetime)
{
	global $dbh;
	// In this example,we don't use $max_lifetime parameter
	// We simply delete all sessions that have expired
	$stmt = "delete from sessions where session_expiration < now()";
	$dbh->query($stmt);
}
session_start ();
// Register the $counter variable as part
// of the session
session_register ("counter");
// Set the save handlers
session_set_save_handler ("on_session_start","on_session_end","on_session_read","on_session_write","on_session_destroy","on_session_gc");
// Let's see what it does
$counter++;
print $counter;
session_destroy();

/***   来自编程之家 jb51.cc（jb51.cc）   ***/