Calculated column with days between previous dates

Hi , digitalPlay 

According to your description, you want to Calculated column with days between previous dates and you want to the previous same date show 0.

For your requirement, this needs to judge the row number, so we need to sort the columns in Power Query first and then create an Index column to meet the requirement.

First, we need to sort the two columns in Power Query Editor:

Then we need to add an index column in it :

Then we can modify your dax code like this:

Column = var temp = TOPN(1,
    FILTER('Run Rate', 'Run Rate'[Project ID] = EARLIER('Run Rate'[Project ID])
    && 'Run Rate'[Milestone Date] <= EARLIER( 'Run Rate'[Milestone Date] ) && 'Run Rate'[Index]<EARLIER('Run Rate'[Index])
),
'Run Rate'[Index])

return
DATEDIFF(MINX(temp,'Run Rate'[Milestone Date]), 'Run Rate'[Milestone Date],DAY)

Then we can get the result as follows:

Thank you for your time and sharing, and thank you for your support and understanding of PowerBI! 

Best Regards,

Aniya Zhang

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