Count Unique Values in column A when meeting 2 criteria.

Hello,

Apologies, but our servers don't allow uploads/downloads to/from this site. I hope my explanation will suffice!

I have a table of data and a separate summary table in which I want to return a value from the following.

I my data table, in column A are client names, in column B are months expressed as a number and in column C are years.

I am trying to return a count of unique values in column A:A when meeting a specific month (B:B) and a specific year (C:C). There can be multiple instances where one client name can appear within a specific month & year.

The summary table has a row referencing months and a cell to reference the year. I cannot have an exhaustive list of client names to reference as the number can increase or decrease at any time.

Thus far i have been trying various types of FREQUENCY formulae, coupled with COUNTIFS and IF statements, but I only ever manage to get a count, not a count of UNIQUE names.

I hope someone can help! Thanks in advance!

Thank so much. Unfortunately it's returning zero for every month. I have made sure to confirm with CSE but still no joy.

Please see the adapted versions below that refer to the actual sheet I am working on, not the simplified example I gave in my explanation earlier.

Data Table:

MyData Range: ='Data Table'!$C$2:INDEX('Data Table'!$U:$U,MATCH(REPT("z",255),'Data Table'!$C:$C))

Column C: Client Names
Column S: Month
Column U: Year


[U]Summary Table:[\U]

Formula: {=COUNT(1/FREQUENCY(IF(INDEX(MyData,0,19)=D$8,IF(INDEX(MyData,0,21)=$D$6,IF(INDEX(MyData,0,3)<>"",MATCH(INDEX(MyData,0,3),INDEX(MyData,0,3),0)))),ROW(INDEX(MyData,0,3))-MIN(ROW(INDEX(MyData,0,3)))+1))}

Cell D6: Year
Cell D8: Month


Please note that for the INDEX functions i have tried referencing the column number by both the normal A=1, B=2 etc AND in relation to the MyData range (ie C=1, D=2 etc..)

Thanks so much for your help!

You are a legend.

This is perfect and now I can make applications to other criteria too!

Can't thank you enough!

Brilliant!