Count unique values between dates

Hi all,

I have a data range that is around 350,000 rows and 52 columns, I am trying to count the number of unique values in a month but also excluding the previous months data if there is a duplicate in the previous month. Its hard to explain so below is a small example;

column A is a name, column B is transaction type and C transaction date.

So line 2 would show Adam Debit 01/01/2016
line 3 would show Adam Debit 02/01/2016

With those i only want to count them once, but if debit on line 3 was BACS, I want to count that as a unique, then when I get to Feb, I want to count the same spec, but exclude the Jan duplicates as well (so they only show as a new client in Jan).

I have tried a countif(frequency array but due to the size of the file it wont work (or may be working but after an hour lunch of letting them calculate it still hadn't completed so was unreasonable), I also use Qlikview but am new to it so would prefer to use excel, if thats not possible please advise and I will focus on the SQL for Qlikview for this.

Any help would be appreciated.

Thanks
Dustin

Hi,

Yeah I am looking at that at the moment and trying to them show snapshots from the pivot in a dashboard I have. Its also proving quite a challenge to get what i want that way as it will show the lists in a slightly more compact format to the raw data, but then I will have to use the countif(frequency formula on that which again crashes the report (still 145k rows).

Thanks for reply.
Dustin