php將session中的數據保存到mysql

php的session默認是以文件方式保存在服務器端，而且在客戶端使用cookie保存變量，這就會出現一個問題，當一個用戶因爲某種安全緣由關閉了 瀏覽器的cookie，程序中的session相關操做將沒法執行。所以，若是能以數據庫保存session數據，將不受客戶端設置的限制，而且在性能和 擴展性等方面有一個飛躍。程序中使用關鍵函數是session_set_save_handler，同時要將php.ini裏的 session.save_handler = files 改成 user。這裏咱們討論的環境是linux(freesd)+apache+mysql+php。 數據表結構：[sessions] CREATE TABLE sessions (  sesskey char(32) not null,  expiry int(11) unsigned not null,  value text not null,  PRIMARY KEY (sesskey)  ); 程序代碼：[session_inc.php] <?php $SESS_DBHOST = "yourhost"; /* database server hostname */ $SESS_DBNAME = "yourdb"; /* database name */ $SESS_DBUSER = "youruser"; /* database user */ $SESS_DBPASS = "yourpassword"; /* database password */ $SESS_DBH = ""; $SESS_LIFE = get_cfg_var("session.gc_maxlifetime"); function sess_open($save_path, $session_name) {     global $SESS_DBHOST, $SESS_DBNAME, $SESS_DBUSER, $SESS_DBPASS, $SESS_DBH; if (! $SESS_DBH = mysql_pconnect($SESS_DBHOST, $SESS_DBUSER, $SESS_DBPASS)) {         echo "<li>Can't connect to $SESS_DBHOST as $SESS_DBUSER";         echo "<li>MySQL Error: " . mysql_error();         die;     } if (! mysql_select_db($SESS_DBNAME, $SESS_DBH)) {         echo "<li>Unable to select database $SESS_DBNAME";         die;     } return true; } function sess_close() {     return true; } function sess_read($key) {     global $SESS_DBH, $SESS_LIFE; $qry = "SELECT value FROM session_tbl WHERE sesskey = '$key' AND expiry > " . time();     $qid = mysql_query($qry, $SESS_DBH); if (list($value) = mysql_fetch_row($qid)) {         return $value;     } return false; } function sess_write($key, $val) {     global $SESS_DBH, $SESS_LIFE; $expiry = time() + $SESS_LIFE; //過時時間     $value = addslashes($val); $qry = "INSERT INTO session_tbl VALUES ('$key', $expiry, '$value')";     $qid = mysql_query($qry, $SESS_DBH); if (! $qid) {         $qry = "UPDATE session_tbl SET expiry = $expiry, value = '$value' WHERE sesskey = '$key' AND expiry > " . time();         $qid = mysql_query($qry, $SESS_DBH);     } return $qid; } function sess_destroy($key) {     global $SESS_DBH; $qry = "DELETE FROM session_tbl WHERE sesskey = '$key'";     $qid = mysql_query($qry, $SESS_DBH); return $qid; } function sess_gc($maxlifetime) {     global $SESS_DBH; $qry = "DELETE FROM session_tbl WHERE expiry < " . time();     $qid = mysql_query($qry, $SESS_DBH); return mysql_affected_rows($SESS_DBH); } session_set_save_handler( "sess_open", "sess_close", "sess_read", "sess_write", "sess_destroy", "sess_gc"); session_start(); ?> 完成以上步驟後，在程序中使用require("session_inc.php")來代替session_start()便可，其餘的session函數仍是象之前同樣的方法調用。