How to save session using database_PHP tutorial

PHP's session is saved as a file on the server side by default, and cookies are used to save variables on the client side. This will cause a problem. When a user turns off the browser's cookies due to some security reasons, the session-related operations in the program will not be executed. Therefore, if session data can be saved in the database, it will not be restricted by client settings, and there will be a leap in performance and scalability. The key function used in the program is session_set_save_handler, and session.save_handler = files in php.ini must be changed to user. The environment we are discussing here is linux(freesd)+apache+mysql+php.

Data table structure: [sessions]
CREATE TABLE sessions (
sesskey char(32) not null,
expiry int(11) unsigned not null,
value text not null ,
PRIMARY KEY (sesskey)
);

Program code: [session_inc.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 "

Can't connect to $SESS_DBHOST as $SESS_DBUSER";
echo "

MySQL Error: " . mysql_error();
die;
}

if (! mysql_select_db($SESS_DBN AME, $ SESS_DBH)) {
   echo "

Unable to select database $SESS_DBNAME";
   die;
  }

 return true; 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; //Expiration time
$value = addslashes($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();
?>

After completing the above steps, use require("session_inc.php" in the program ) instead of session_start(), other session functions are still called in the same way as before.


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