Sum distinct in set expression?

[Anonymous]

Hello, assuming I have the following table

Computer_ID	Date_Used	On_State
1	1.01.2017	1
2	1.01.2017	1
3	1.01.2017	1
1	1.01.2017	1
2	1.01.2017	1
1	1.01.2017	1
3	3.01.2017	1

how can I sum all the days all the computers have been used on "On_State" = 1 without adding the duplicates? Is there any way to use DISTINCT in Sum's Set Expression?

I'm looking for the following output for the said expression(in a PivotTable), given the table above:

Computer_ID	Days_used
1	1
2	1
3	2

[sunny_talwar · Accepted solution]

May be this

Count(DISTINCT Date_Used)

[Anonymous]

Thanks, it works!