On May 28, 5:25 pm, adimar wrote:
I have a very large table of non-unique items shipped; the table contains
“item id” and “ship date” columns.

I need to find the number of unique “item id-s” shipped in a given
timeframe, ex. 01/01/08 - 03/31/08

I’ve tried using the commonly quoted solution:
=SUMPRODUCT((A1:A10<"")/COUNTIF(A1:A10,A1:A10&""))

Somehow, I cannot get the additional check for timeframe to work in the
above formula, something like:
=SUMPRODUCT((A1:A10<"")/COUNTIF(A1:A10,A1:A10&"")*(B1:B10 = C1)*( B1:B10
<= C2))

I would appreciate suggestions for array formula solutions.

Thank you.

Google "morefunc". They have a free UDF that supposedly does exactly
this.