COVID-19 US Tracking Sample - DAX Formula for Daily Death measure

[MaggieWang]

Hi, I am practicing writing DAX formulas and come across the following measure from the "COVID-19 US Tracking Sample" file.

      Daily deaths =

      VAR __CountyName = 'COVID'[County Name]

      VAR __State = 'COVID'[State]

      VAR __Yesterday =  DATEADD(COVID[Date],-1,DAY)

      VAR __TodaysDeaths = 'COVID'[Deaths]

      RETURN  __TodaysDeaths - CALCULATE(

          SUM('COVID'[Deaths]) ,

          FILTER(

              COVID,

              COVID[Date] = __Yesterday &&

              COVID[County Name] = __CountyName &&

              COVID[State] = __State

          )

      ) + 0

Everything makes perfect sense except the last "+ 0" part. Why was the + 0 required at the end of the measure, was it for providing an initial value for doing the SUM? Many thanks.

[Anonymous]

If you remove +0, you'll see immediately why it's there. And no, it's not necessary unless you want to see 0 instead of BLANK...

[CNENFRNL · Accepted solution]

Hi, @MaggieWang , it's a common trick to convert BLANK() to 0, i.e. when this part of measure

__TodaysDeaths - CALCULATE(
          SUM('COVID'[Deaths]) ,
          FILTER(
              COVID,
              COVID[Date] = __Yesterday &&
              COVID[County Name] = __CountyName &&
              COVID[State] = __State
          )
      )

returns BLANK(), it can be converted to 0.

Try this measure to see the affect

Test = BLANK() + 0