Taking Distinct count after calculating a measure

[Anonymous9999]

I have a database for students. Student name, school joining date, teacher assigned,
Date of termination, expected graduation date.
Here since I have to take count for every date column by month, I have created a calendar table and gave direct relationship with joining date of student
As we know same teacher teaches many students, we need cumulative distinct count of the teacher after deducting
the count of students terminated and graduated during that month.Below is my dataset

Joining Date	Student name	Teacher	Terminated date	Graduated date
1/1/2022	A	I		3/1/2022
1/2/2022	B	J
2/3/2022	D	I	3/25/2022
2/4/2022	E	K
3/5/2022	F	K	4/2/2022
4/5/2022	G	L
4/5/2022	H	M

Expected result

Jan	2
Feb	3
March	2		we 1st consider all students joined until march.then we have to ignore the row which was terminated and graduated in march. Then consider all the teachers from Jan to march and take their distinct count
April	4		Same as march calculation, we ignore any termination and graduations happned in april and then take disticnt count

[Anonymous9999]

This did not work for me. It is giving very different number which I am unable to identify how it is coming

[FreemanZ · Accepted solution]

hi @Anonymous9999 

try to create plot a table visual with the measure like this:

Result = 
VAR CurrentMonth = MONTH(MAX(TableName[Joining Date]))
RETURN
CALCULATE(
    DISTINCTCOUNT(TableName[Teacher]),
    FILTER(
        ALL(TableName),
        MONTH(TableName[Joining Date])<=CurrentMonth            
    )
) -
CALCULATE(
    DISTINCTCOUNT(TableName[Teacher]),
    FILTER(
        ALL(TableName),
        OR (
            AND ( 
                MONTH(TableName[Terminated Date])<>BLANK(), 
                MONTH(TableName[Terminated Date])=CurrentMonth
            ),
            AND( 
                MONTH(TableName[Graduated Date])<>BLANK(), 
                MONTH(TableName[Graduated Date])=CurrentMonth
            )
        )
    )
)

i tried and it worked like this:

the dataset: