Retrieve all titles for which the royalty is unknown. (5 points)

This is what I have and the error that I am getting.

title id (PK, tid (varchar(6)), not title (varchar(80), not null) type (char(12), not null) oe pub_id (FK, char(4), null) price (money, null) advance (money, null) E royalty (int, null) ytd-sales (int, null) B notes (varchar(200), null pubdate (datetime, not null)