The value for 'when' cannot be determined. Either the column doesn't exist

[chu_en]

Dear Community,

I have a date fields called "When", and i wanna count week from month to get average

and when i'm create new measure from it then the error show "The value for 'when' cannot be determined. Either the column doesn't exist, or there is no current row for this column."

but i can use is, just cannot measure it,

Help me please

Thank you

Best Regards

[AllisonKennedy · Accepted solution]

You will probably need to set up a DimDate table for this, which will have a column for "Week of Month" and 'Week of Year", then you can use AVERAGEX(Values(DimDate[WeekOfMonth]), SUM(Table[Attendance])) and put that in a visual with DimDate[Month]

https://excelwithallison.blogspot.com/2020/04/dimdate-what-why-and-how.html

Hope that helps!

[AllisonKennedy]

We need more info to help you please - what formula are you trying to use for DAX Measure and what other fields are you trying to use in the visual where you are seeing the error? How are these fields/tables related to 'when'? 



Are you trying to average weeks/month across the year or the value in another column aggregated weekly?

[chu_en]

what i'm trying to use formula is

sum(attendance) / count (week of month)

eg.

WHEN, ATTENDANCE

2020-10-04, 2

2020-10-11, 4

2020-10-18, 4

2020-10-25, 2

Total Oct is 12, and devide by total of week is 4 then Average of Oct is 3

and i dont know how to get total week of month, cause i'm creating measure but "when" cannot be determined.

Thank you  @AllisonKennedy 

[AllisonKennedy · Accepted solution]

You will probably need to set up a DimDate table for this, which will have a column for "Week of Month" and 'Week of Year", then you can use AVERAGEX(Values(DimDate[WeekOfMonth]), SUM(Table[Attendance])) and put that in a visual with DimDate[Month]

https://excelwithallison.blogspot.com/2020/04/dimdate-what-why-and-how.html

Hope that helps!

[chu_en]

Wow, its worked, but one more question, how do i edit in the formula the week of the month, starting the first sunday of the month count as week 1

eg.

thank you @AllisonKennedy 

[AllisonKennedy · Accepted solution]

You're welcome @chu_en 

To get the week to start on Sunday, add the optional argument to Week of month function: 

https://docs.microsoft.com/en-us/powerquery-m/date-weekofmonth

Sunday corresponds to 0 day of the week, so: 

Click the settings cog next to insert Week of Month column then update code to: 

Date.WeekOfMonth([Date],0)

Or the entire code for table below: 

let
startDate = #date(2019, 1, 1),
endDate = Date.From(DateTime.LocalNow()),
Dates = List.Dates(startDate, Duration.Days(endDate - startDate), #duration (1,0,0,0)),
#"Converted to Table" = Table.FromList(Dates, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
#"Renamed Columns" = Table.RenameColumns(#"Converted to Table",{{"Column1", "Date"}}),
#"Changed Type" = Table.TransformColumnTypes(#"Renamed Columns",{{"Date", type date}}),
#"Inserted DateKey" = Table.AddColumn(#"Changed Type", "DateKey", each Date.ToText([Date],"yyyyMMdd"), type text),
#"Inserted Year" = Table.AddColumn(#"Inserted DateKey", "Year", each Date.Year([Date]), Int64.Type),
#"Inserted Quarter" = Table.AddColumn(#"Inserted Year", "Quarter", each Date.QuarterOfYear([Date]), Int64.Type),
#"Inserted FY Quarters" = Table.AddColumn(#"Inserted Quarter", "FY Quarter", each if [Quarter] = 1 then "Q4" else if [Quarter] = 2 then "Q1" else if [Quarter] = 3 then "Q2" else "Q3", type text),
#"Inserted Month Name" = Table.AddColumn(#"Inserted FY Quarters", "Month name", each Date.MonthName([Date]), type text),
#"Inserted Month" = Table.AddColumn(#"Inserted Month Name", "Month number", each Date.Month([Date]), Int64.Type),
#"Inserted Week of Year" = Table.AddColumn(#"Inserted Month", "Week of Year", each Date.WeekOfYear([Date]), Int64.Type),
#"Inserted Week of Month" = Table.AddColumn(#"Inserted Week of Year", "Week of Month", each Date.WeekOfMonth([Date],0), Int64.Type),
#"Inserted Day of Year" = Table.AddColumn(#"Inserted Week of Month", "Day of Year", each Date.DayOfYear([Date]), Int64.Type),
#"Inserted Day of Week" = Table.AddColumn(#"Inserted Day of Year", "Day of Week", each Date.DayOfWeek([Date]), Int64.Type),
#"Inserted Day of Month" = Table.AddColumn(#"Inserted Day of Week", "Day of month", each Date.Day([Date]), Int64.Type),
#"Inserted Day Name" = Table.AddColumn(#"Inserted Day of Month", "Day name", each Date.DayOfWeekName([Date]), type text),
#"Inserted FY start" = Table.AddColumn(#"Inserted Day Name", "FY starts", each [Year] + (if [Month number] > 3 then 0 else -1), type number),
#"Inserted FY" = Table.AddColumn(#"Inserted FY start", "FY", each Text.From([FY starts]) & "/" & Text.From([FY starts] + 1), type text)
in
#"Inserted FY"