class DB {

private static $dbserver = "mysql:dbname=db;host=localhost";
private static $dbuser = "root";
private static $dbpass = "";

public static function connectDB() {

    @$dbh = new PDO(self::$dbserver, self::$dbuser, self::$dbpass);
    $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
    $dbh->setAttribute(PDO::MYSQL_ATTR_INIT_COMMAND, 'SET NAMES utf8');

    return $dbh;
}

function insert_data($data) {
    $error = NULL;
    try {
        $dbh = DB::connectDB();
        $dbh->beginTransaction();

        $query_insert_1 = 'INSERT INTO table (f1, f2, f3) VALUES (?,?,?)';
        $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $stmt = $dbh->prepare($query_insert_1);
        $stmt->execute(array($d1, $d2, $d3));

        $last_insert_id = $dbh->lastInsertId();

        $query_insert_2 = 'INSERT INTO table2 (f4, f5, f6) VALUES (?,?,?)';
        $stmt = $dbh->prepare($query_insert_2);
        $stmt->execute(array($last_insert_id, $d4, $d5));

        $dbh->commit();
    }
    catch(Exception $e) {
        $dbh->rollback();
        $error = $e->getMessage();
    }
    $return = new Result($error ? 1 : 0, $error ? 0 : 1, $error ? $error : '', NULL);
    error_log(print_r($error,1));
    return $return;
}