$info_query = mysql_query("insert into ticket_info (userid, subject, case, category, date, usernick)values('$user_id', '$subject', '1', '$category', '$datetime', '$user_nick')");
$info_id = mysql_insert_id();
$messages_query = mysql_query("insert into ticket_messages (senderid, message, sendernick, ticketid, date)values('$user_id', '$message', '$user_nick', '$info_id', '$datetime')");

DELIMITER $$
CREATE TRIGGER asdf AFTER INSERT ON ticket_info FOR EACH ROW
BEGIN
INSERT INTO ticket_messages (senderid, message, sendernick, ticketid, date) VALUES (NEW.userid, '$message', '$user_nick', '$info_id', NOW())
END
$$

DELIMITER ;