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I think that we need a better data set if we're going to give a good answer.  Your current data set only has one record that will be deleted.  We...

Assuming that you data does not contain any records for the current month, this should work.

;
WITH CTE AS
(
    SELECT StoreId, sales, DENSE_RANK() OVER(ORDER BY...

When working with dates, you DO NOT want to use Year and Month (unless you have a calendar table).  You want to use the first day of the month.  Using Year/Month...

When responding to a long post, I sometimes like to interleave my answers in the places that I'm responding to.  I used to be able to just add a closing...

Reported as spam.

I'm getting the same error.

Also, it's pointless to have both a DISTINCT keyword and a GROUP BY in the same section of a query.  The GROUP BY has an implicit DISTINCT in it, and...

A common approach is to reference a calendar table, especially if you need to exclude holidays as well as weekends.  You just count the number of days that qualify.