$con=mysqli_connect("abc", "abc", "abc", "abc");
if (mysqli_connect_errno()) {
    echo "Failed to connect to MariaDB: " . mysqli_connect_error();
}
/* check connection */
if ($con->connect_errno) {
    printf("Connect failed: %sn", $con->connect_error);
    exit();
}

$t = new Timer($con);
// lots of irrelevant code
unset($t);

class Timer {
    private $time = null;
    private $con;
    public function __construct($con) {
        $this->$con = $con;
        $this->time = time();
        echo 'Working - please wait..<br/>';
    }

    public function __destruct() {
        $basename = basename($_SERVER['PHP_SELF']);
        $query = "SELECT ScriptID FROM scripts WHERE `ScriptURL` = '$basename';";
        $scriptIDResult = mysqli_fetch_assoc(mysqli_query($con, $query)) or die(mysqli_error($con));
        $t->scriptID = $scriptIDResult['ScriptID'];
        $elapsed = (time()-$this->time);
        echo '<br/>Job finished in '.($elapsed).' seconds.';
        $scriptQuery = "UPDATE `scriptruns` SET `ScriptExecutedTime` = '$elapsed', `ScriptRunDate` = NOW() WHERE `ScriptID` = '$scriptID'";
        $result = mysqli_query($con, $scriptQuery) or die(mysqli_error($con));
    }
}