Good afternoon,

I'm looking for a formula where I can use multiple criteria then count unique values in a column.

For example we have 3 columns

Column A = Date
Column B = Hour
Column C = Staff

I want something like 
=Sumproduct((A1:A100="26/11/13")*(B1:B100=8)*(C1:C100=CountUniqueEntries))
So if the table looked like this

A B C
26/11 8 John Smith
26/11 8 David White
26/11 8 John Smith

I would want the answer to come back with 2 (2 Unique Entries in Column C)

Thanks in advance

DJ