you can create a new table and sort the category column by sort column

do not create relationship between two tables

then create a measure

MEASURE =
SWITCH (
    TRUE (),
    SELECTEDVALUE ( 'Table (2)'[category] ) = "A", CALCULATE ( SUM ( 'Table'[value] ), 'Table'[category] = "A" ),
    SELECTEDVALUE ( 'Table (2)'[category] ) = "B", CALCULATE ( SUM ( 'Table'[value] ), 'Table'[category] = "B" ),
    CALCULATE ( SUM ( 'Table'[value] ) )
)