I have a dataset in PowerPivot and need to find a way to flag ONLY the first occurrence of a customer sub event
Context: Each event (COLUMN A) can have X number of sub events (COLUMN B), I already have a flag that identifies a customer event based on multiple criteria's (COLUMN D)... What I need is a way to flag only the first occurrence of a customer sub event within each event, I've added a fake COLUMN E to illustrate how the flagging should work.
UPDATE Additional situation - Having duplicated customer sub_events but only need to flag the first sub_event... should look like this: