What are the ids of all moviest hat have not been reviewed by Britanny Harris?
SELECT mID FROM Rating EXCEPT SELECT T1.mID FROM Rating AS T1 JOIN Reviewer AS T2 ON T1.rID  =  T2.rID WHERE T2.name  =  "Brittany Harris"
movies not reviewed by Britanny Harris refers to selecting movie IDs from the Rating table except those reviewed by Britanny Harris; using EXCEPT to exclude; joining Rating and Reviewer tables on reviewer ID to filter by reviewer name;