How to do group B - group A?2 followers
Use case: For column A, I want to know how many new string that're never seen before has added in the past week, and I want to be able to schedule this job to run weekly.
Create a group A (every unique string before last week) is easy. GROUPBY can do it, so does creating a group B (every unique string last week), but How do I do the set complement? i.e. Group B - Group A.