We have a multi-row, multi-column spreadsheet. For each unique value in
Column "A", we want to count the unique values in Column "B".

We tried a pivot table, but get a total count, instead of the unique values.

We then tried a two-step process. 1) we created the unique list in Column A
by Pivot Table or by Autofiter. 2) The formula below (as an array), but
again, it gave a total count, instead of the unique count.

=COUNT(IF('2008-2009 (till Nov) TR'!E2:E5033=Sheet2!H2,COUNT('2008-2009
(till Nov) TR'!D2:D5033),"")).

We also tried the subtotal functional, but it required many steps and many
sheets, because we will repeats using many different conditions.