Excel count rows where column B equals value and value in column A is not a duplicate

Question

I have a table as follows:

A	B
1	happy
1	sad
2	angry
2	sad
3	sad
4	moody
4	thoughtful
5	excited

I need to count the number of times "sad" appears in column B whose value in column A is NOT a duplicate.

I am aware of =COUNTIF(B2:B8, "sad") but I'm stuck there.

Our answer should be 1 since sad only occurs once without a duplicate in A.

Thank you.

Answer 1

Use SuMPRODUCT with a COUNTIFS():

=SUMPRODUCT((B1:B8="Sad")*(COUNTIF(A1:A8,A1:A8)=1))