Measure - Subtract one field from another

Hi spandy34 ,

If [Previous Performance] and [Current Performance] are measures, you can use them directly.

If [Previous Performance] and [Current Performance] are columns, you need to use SUM()/MAX()/MIN() function to use them. Measure will return aggregation.

Measure:

Diff in Per No Previous =
IF (
    ISBLANK ( SUM ( 'TableName'[Previous Performance] ) ),
    0,
    SUM ( 'TableName'[Current Performance] )
        - SUM ( 'TableName'[Previous Performance] )
)

Best Regards,

Rico Zhou

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