Counting and Unique values

Hi

I have 2 sheets, one with users and a tool they have been using, and one with a list of unique users, I would like to count how many unique users are using a tool. The sheets are set up like so,

Sheet 1
User Tool (number of uses)
abcdefg 1
hijklmn 5
1234567 1
1234567, abcdefg, opqurst 2
wxyz123 0

Sheet 2 Have they used the tool

abcdefg
hijklmn
1234567
wxyz123
opqurst

So yes, I am trying to count whether or not the unique users have used the tool, this is a simplifed version as my data set runs into the thousands. I was using the countifs function, but that doesnt count properly if theres more than one user in the group. Can anyone help me please?

maybe something like:
=SUM(IF(SUMIF(Sheet1!A1:A5,Sheet2!D1:D5,Sheet1!B1:B5)>0,1,0))
as an array formula (confirm with ctrl+shift+enter).

Where A1:A5 is your list of users in sheet1 and b1:B5 is the number of times they used the tool. D1:D5 is your list of unique users.

Hi

Thanks for the help so far, neither of those solutions seem to work. The formula I have been using is
=COUNTIFS(Sheet1!$F$2:Sheet1!$F$3705,Sheet3!$A6,Sheet1!$R$2:Sheet1!$R$3705,">=1")

where Sheet1 F2;F3705 is my list of users in sheet 1, A6 is the unique user I am trying to find the data for in sheet 3, and Sheet 1 R2:R3705 is the number of times they used thetool. I simply drag the formula down to check against all users as the Sheet3 term changes.

Any further tips?

Never mind I got it to work, thanks for your help