Showing Last 03 Month Average Sales Rolling

Hi ADSL 

Please try this:

Here I create a Measure:

MEASURE =
VAR _Slicer_Month =
    MONTH ( MAX ( 'Calendar'[Date] ) )
VAR _Slicer_Year =
    YEAR ( MAX ( 'Calendar'[Date] ) )
VAR __Month =
    SUMMARIZE (
        SELECTCOLUMNS (
            CALENDAR (
                DATE ( _Slicer_Year, _Slicer_Month - 3, 1 ),
                DATE ( _Slicer_Year, _Slicer_Month - 1, 1 )
            ),
            "_Month", FORMAT ( [Date], "YYYY-mm" )
        ),
        [_Month]
    )
VAR _vtable =
    SUMMARIZE (
        ALL ( 'Sales Order' ),
        Customers[Customer Name],
        'Sales Order'[Month],
        "_SUMSales", SUM ( 'Sales Order'[Sales_Amt] )
    )
VAR _vtable2 =
    SUMMARIZE (
        _vtable,
        'Customers'[Customer Name],
        "_AVG",
            VAR _currentName =
                SELECTEDVALUE ( Customers[Customer Name] )
            RETURN
                AVERAGEX (
                    FILTER ( _vtable, [Month] IN __Month && [Customer Name] = _currentName ),
                    [_SUMSales]
                )
    )
RETURN
    IF (
        SELECTEDVALUE ( Customers[Customer Name] )
            IN SELECTCOLUMNS ( TOPN ( 10, _vtable2, [_AVG], DESC ), [Customer Name] ),
        SUM ( 'Sales Order'[Sales_Amt] )
    )

Add it to the table visual, the result is as follow:

Best Regards

Zhengdong Xu
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