Count unique values based on date

[Charly123]

Hello Excel experts,

I have the following table:

(A) Date ||| (B) ID
(1) 20/10/2019 ||| 12345
(2) 20/10/2019 ||| 54321
(3) 20/10/2019 ||| 43251
(4) 20/10/2019 ||| 12345
(5) 19/10/2019 ||| 11111
(6) 19/10/2019 ||| 22222
(7) 19/10/2019 ||| 33333
(8) 19/10/2019 ||| 44444

And I would like to count the unique IDs per date on that table, getting as result something like this:

Date ||| Unique count of IDs
20/10/2019 |||| 3
19/10/2019 |||| 4


Any help? Can't make it work by myself using google's help.

[PaulM100]

Try: =SUM(--(FREQUENCY(IF($A$2:$A$10=$E5,$B$2:$B$10),$B$2:$B$10)>0)) as an array formula confirmed with Ctrl+Shift+Enter

[Glenn Kennedy]

If that's not it...

Will you please attach a SMALL sample Excel workbook (10-20 rows of data is usually enough)? However, please give us an indication of the approximate number of rows of data you want the solution to work with (100, 1000, 100,000 or whatever). Please DO NOT attach a picture of an Excel sheet (I do not have the patience to re-type any/all your stuff before starting).

1. It does NOT have to be your real sheet - mock up a SAMPLE if you need to. But not 1000's of rows!!! It makes manual checking so tedious. Whatever you do... make sure that all confidential information is removed first!!

2. Make sure that your sample data are truly REPRESENTATIVE of your real data. For example, don't show text in a column if it's really a number. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

3. Make sure that your desired solution is also shown (mock up the results manually). To be honest, I am not interested in seeing a non-working formula... or a pile of blank cells. However, I am very interested in seeing your EXPECTED results in their EXPECTED location.

4. Try not to use merged cells. They cause lots of problems and are DEFINITELY best avoided!

Unfortunately the attachment icon doesn't work at the moment. So, to attach an Excel file you have to do the following: Just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

[Charly123]

This worked, thank you very much.

Try: =SUM(--(FREQUENCY(IF($A$2:$A$10=$E5,$B$2:$B$10),$B$2:$B$10)>0)) as an array formula confirmed with Ctrl+Shift+Enter

However, I have around 500.000 rows to play with and the array formulas are consuming too much resources. Is there another way you would recommend?

[Glenn Kennedy]

Possibly. Post a sample sheet. I don't want to have to figure out what your sheet looks like and then reproduce it myself.

[Charly123]

Apologies, attached you have a sample sheet.

[Glenn Kennedy]

Here's an alternative. No idea if it's any better!!

=SUM(INDEX(($B$5:$B$15=E8)/COUNTIFS($B$5:$B$15,$B$5:$B$15&"",$C$5:$C$15,$C$5:$C$15&""),0))

Just use Enter....