I'm trying to write a Roll-up Summary to Count the Value of Records that were created This Week and Last Week.  However, since Roll-up Summary fields do not support Dynamic Date parameters I need to somehow create a Formula Field that returns a "Yes" or "No" value if the record was created Last Week or This Week.

Does anyone have a clever way of creating a Formula Field on an Object that would return the value of Yes or No based on the following:

1 Field
IF(CreatedDate = "This Week", "This", IF(CreatedDate = "Last Week", "Last", "Neither))

Then I can write a Roll-up Summary to Sum Records where Field = This and a second Rollup Summary where Field = Last.

or

2 Fields
Field 1: IF(CreatedDAte = "This Week", "Yes", "No")

Field2: IF(CreatedDAte = "Last Week", "Yes", "No")

Then I can write a Roll-up Summary to Sum Records where Field1 = Yes and a second Rollup Summary where Field2 = Yes.


Thank you.