SSRS 获取筛选组数

Question

Working with dynamics 365 reports has brought me to the next issue. Because FetchXML doesn't support NOT EXISTS condition, i have to filter data inside report.
The case is that I have like 7000 rows and I group them by account (around 2000 groups).
And used filter on group.
And after that i've got:
| account | data |
|----------| ----------|
| apple___ | some_data |
| samsung| more_data |
| lg_______ | next_data |
So after grouping and filtering i have only 3 groups (accounts).
But how to achieve this value (3) in report?
CountDistict(Field.account.Value) includes all nonfiltered accounts.
CountDistict(Field.account,Value, "filteredAccGroup") outside the group throws "The Value expression for the text box 'Textbox145' has a scope parameter that is not valid for an aggregate function." Have no other ideas.
I need the count (or number) of all filtered groups. Current index of group would also be nice.
Thanks.

Solution:
Found the solution. But not sure this is the optimal one.
Outside the group:

CountDistinct(iif(min(Fields!date.Value, "account_group") >= CDate("01/01/2021"),
Fields!account.Value, nothing))

Under iif is the condition i have filtered the group.

Answer 1

Assuming your dataset is called DataSet1 then the following should work.

=CountDistinct(Fields!account.Value, "DataSet1")

As usual, the scope has to be in quotes and is case sensitive.

Answer 2

Outside the group:

 CountDistinct(iif(min(Fields.date,Value, "account_group") >= CDate("01/01/2021"). Fields,account.Value, nothing))

Under iif is the condition i have filtered the group.