Formula for counting duplicate rows only once combined with multiple criteria.

[jupstin]

Here's what I'm trying to do. I have a worksheet like this:

ID	Date	Transfer	Other
12345	5/4/2019		5
12345	5/4/2019		4
12345	5/4/2019		6
98789			6
98789			4
65454	5/4/2019	Y	2
91595	5/4/2019	Y	1
75357		Y	9
75357		Y	1

What I would like is a formula to count every ID one time that has a value in the Date column and no value in the Transfer column. All rows will always have an ID and at least some other data.

My problem is that I can get a count of all rows what have a value in Date and no value in Transfer, but it includes duplicate ID entries, which I don't want.

With the table above, I would like to return the value "1" because ID 12345 represents 1 person, but I can only manage to get the value "3" because ID 12345 is repeated 3 times.

I hope that makes sense. I know I could get the answer I'm looking for by removing duplicates, but I'd like to avoid that if possible. Thanks

[#2]

You can use this formula:
=SUMPRODUCT(1/COUNTIF(A2:A10,A2:A10)*
(B2:B10<>"")*
(C2:C10=""))

[#3]

@Twifoo 

This is similar to something I'm trying to figure out, but the formula you describe doesn't work for me.  

I'm working with content in which I'm trying to get a count of specific types of training but only count the unique sessions.  This is a subset of the data:

Type of T/TASession	Title
In Person Presentation	Key Financial Management Concepts and Processes
In Person Presentation	Budget Review
Office Hours	Budget Review, TA call
Live Webinar	Best Practices in Budget Development
Office Hours	Budget Review, TA call
Live Webinar	GO Certification Steps
Live Webinar	GO Certification Steps
Live Webinar	January 2020 Third Thursdays
Recorded Instruction	January 2020 Third Thursdays
Recorded Instruction	January 2020 Third Thursdays
Instruction only, no demo	Manual Holds and Manual Reviews
Live Webinar	June 2020 Third Thursdays
Instruction only, no demo	Pre-Award Spending Approval
Instruction only, no demo	Manual Holds and Manual Reviews

So where the "Office Hours" includes two entries for "Budget Review, TA call", I only want to count the value of one, since the second is a repeated session.  I tried using COUNTIFS but need the ability to automatically filter the duplicates.  

Any ideas?