Need help with DAX previous quarter

Hi Lili304 ,

Here I create a sample to show you how to achieve your goal.

My Sample:

Data Model:

Measure:

Previous = 
VAR _PREVIOUS_QUARTER =
    CALCULATE (
        MAX ( DimPeriod[Period] ),
        FILTER (
            ALLEXCEPT ( 'Table', 'Table'[Item] ),
            'Table'[Period] < MAX ( DimPeriod[Period] )
        )
    )
VAR _RESULT =
    CALCULATE (
        SUM ( 'Table'[Values] ),
        FILTER (
            ALLEXCEPT ( 'Table', 'Table'[Item] ),
            'Table'[Period] = _PREVIOUS_QUARTER
        )
    )
VAR _MAXPERIOD =
    MAX ( 'Table'[Period] )
RETURN
    IF ( SELECTEDVALUE ( DimPeriod[Period] ) > _MAXPERIOD, BLANK (), _RESULT )

Diff = SUM('Table'[Values]) - [Previous]

Result is as below.

Best Regards,
Rico Zhou

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