A simple way is to do a Countif
=Countif(B1:B6,"John")

"Neville" wrote:

I have the following database table in Excel:

A B
1 1 Sep John
2 1 Sep Fred
3 1 Sep John
4 2 Sep John
5 3 Sep Fred
6 3 Sep John

How can I count the number of unique dates in which John applies? The answer
should be 3, i.e. 1 Sep, 2 Sep and 3 Sep.