Sum of available people in a certain month

[Olia]

Hello,

I'm trying to create a measure that will show how many people are "available" in the current month.

As an example, here's a data from 2 (!) people: Jessia (who can fullfill 2 roles) and Sandy:

Name	Role	Available from month
Jessica	Accountant	10
Jessica	Financial Controller	10
Sandy	Financial Controller	11

As result I need to see that we have 1 person available in October, but 2 people available in November (since Jessica has become available previously, and is still available).

Somehow adding SUM and DISTINCTCOUNT doesn't work... and then there are the months... suggestions? 

[PattemManohar · Accepted solution]

@Olia Please try using below expression as "New Column"

TotalAvailable = 
VAR CurrMonth = CALCULATE(DISTINCTCOUNT(RoleAvailable[Name]),FILTER(ALL(RoleAvailable),RoleAvailable[Month]=EARLIER(RoleAvailable[Month])))
VAR PrevMonth = CALCULATE(DISTINCTCOUNT(RoleAvailable[Name]),FILTER(ALL(RoleAvailable),RoleAvailable[Month]=EARLIER(RoleAvailable[Month])-1))
RETURN CurrMonth + PrevMonth

[Olia]

thank you @PattemManohar!