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SteveIOW's avatar
SteveIOW
Helper II
3 years ago
Solved

Using Variables in Summarize

Hi, wondering if anyone understands what is happening here.

 

I have built a table using summarize.

To start with I used 4 variables:

VAR vC2021 = CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2020-21")
VAR vC2122 = CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2021-22")
VAR vNF2021 = IF(CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2020-21") = 0,  1, 0)
VAR vNF2122 = IF(CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2021-22") = 0,  1, 0)
 
I plugged these in using RETURN:
SUMMARIZE(
MainFacts,
MainFacts[Provider_Code],
"Count2021", vC2021,
"NullFlag2021", vNF2021,
"Count2122", vC2122,
"NullFlag2122", vNF2122
)
and it doesn't work... I get...
 
However, if I repace the variables with the actual statement it does work...
SUMMARIZE(
MainFacts,
MainFacts[Provider_Code],
"Count2021", CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2020-21"),
"NullFlag2021", IF(CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2020-21") = 0,  1, 0),
"Count2122", CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2021-22"),
"NullFlag2122", IF(CALCULATE(DISTINCTCOUNT(MainFacts[EpisodeNumber]), MainFacts[Period] = "FY2021-22") = 0,  1, 0)
)

 

What on earth is going on??

 

cheers

 

Steve

Need Help
  • johnt75's avatar
    johnt75
    3 years ago

    Variables in DAX aren't really variables, they're constants. They are only calculated once, when they are defined, which is why you're seeing the same wrong values for each row.

    Its also worth pointing out that it is not best practice to use SUMMARIZE to produce calculated columns as performance is poor and you can get unexpected results. It is better to use SUMMARIZE to do the grouping and then use ADDCOLUMNS to produce the calculations, so your code would become

    My Table =
ADDCOLUMNS (
    SUMMARIZE ( MainFacts, MainFacts[Provider_Code] ),
    "Count2021",
        CALCULATE (
            DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
            MainFacts[Period] = "FY2020-21"
        ),
    "NullFlag2021",
        IF (
            CALCULATE (
                DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
                MainFacts[Period] = "FY2020-21"
            ) = 0,
            1,
            0
        ),
    "Count2122",
        CALCULATE (
            DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
            MainFacts[Period] = "FY2021-22"
        ),
    "NullFlag2122",
        IF (
            CALCULATE (
                DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
                MainFacts[Period] = "FY2021-22"
            ) = 0,
            1,
            0
        )
)

4 Replies

  • johnt75's avatar
    johnt75
    Super User
    3 years ago

    Variables in DAX aren't really variables, they're constants. They are only calculated once, when they are defined, which is why you're seeing the same wrong values for each row.

    Its also worth pointing out that it is not best practice to use SUMMARIZE to produce calculated columns as performance is poor and you can get unexpected results. It is better to use SUMMARIZE to do the grouping and then use ADDCOLUMNS to produce the calculations, so your code would become

    My Table =
ADDCOLUMNS (
    SUMMARIZE ( MainFacts, MainFacts[Provider_Code] ),
    "Count2021",
        CALCULATE (
            DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
            MainFacts[Period] = "FY2020-21"
        ),
    "NullFlag2021",
        IF (
            CALCULATE (
                DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
                MainFacts[Period] = "FY2020-21"
            ) = 0,
            1,
            0
        ),
    "Count2122",
        CALCULATE (
            DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
            MainFacts[Period] = "FY2021-22"
        ),
    "NullFlag2122",
        IF (
            CALCULATE (
                DISTINCTCOUNT ( MainFacts[EpisodeNumber] ),
                MainFacts[Period] = "FY2021-22"
            ) = 0,
            1,
            0
        )
)
    • Hijaika's avatar
      Hijaika
      Frequent Visitor
      3 years ago

      But what if i wanted to use that variable again in a later calculation? In this case Count2122 for example.

      • johnt75's avatar
        johnt75
        Super User
        3 years ago

        Instead of using ADDCOLUMNS you could use a combination of GENERATE and ROW, the general pattern is something like

        My Table =
GENERATE (
    SUMMARIZE ( 'Table', 'Table'[Column 1], 'Table'[Column 2] ),
    VAR Var1 =
        CALCULATE ( SUM ( 'Table2'[Value] ) )
    VAR Var2 =
        IF (
            Var1 > 0,
            CALCULATE ( SUM ( 'Table2'[Value2] ) ),
            CALCULATE ( SUM ( 'Table2'[Value3] ) )
        )
    RETURN
        ROW ( "Var1", Var1, "Var2", Var2 )
)