Weekofyear doesnt work

[StephenF]

Its telling me 1st of jan 2023 is week 1, its not, its week 53.

I'm in Europe.

Whats a fix I can use as a custom column in the query editor?

[AilleryO]

Hi,

If you want to create a column with ISO week number in your date table here is a step by step formula to calculate week num according to ISO (DateRef is the column with the date in date table) :

//Calculate week num ISO (Europe) in 4 steps
//1. Calculate Thursday of week
InsertCurrThursday = Table.AddColumn(InsertMonthEnding, "CurrThursday", each Date.AddDays([DateRef], -Date.DayOfWeek([DateRef],1) + 3), type date),
//2. Calculate 1st january of the year (cf step 1) 
InsertFirstJan = Table.AddColumn(InsertCurrThursday, "FirstJan", each#date(Date.Year([CurrThursday]),1,1),type date),
//3. Calculate number of days betweeen thursday and 1st january
// (cf step 1 and 2)
InsertDuration= Table.AddColumn(InsertFirstJan, "Duration", each Duration.Days(Duration.From([CurrThursday] - [FirstJan])), type number),
//4. Divide the number of days from step 3 by 7
//round down and add 1
InsertISOWeekNum = Table.AddColumn(InsertDuration, "NumSemISO", each Number.RoundDown([Duration]/7)+1), 
ChangeType5=Table.TransformColumnTypes(InsertISOWeekNum,{{"NumSemISO", Int64.Type}}),
Format2Chiffres=Table.AddColumn(ChangeType5, "SemaineISO", each Number.ToText([NumSemISO],"D2"), type text),// D2 means format with 2 Digits
//Delete unusefull columns
RemovedColumns = Table.RemoveColumns(Format2Chiffres, {"CurrThursday","FirstJan","Duration", "NumSemISO"})

Hope it helps

[v-zhangti · Accepted solution]

Hi, @StephenF 

This is the default result in DAX functions.

If you want January 1, 2023 to be week 53, you can try this method.

Week = 
IF (
    [Date] = DATE ( 2023, 1, 1 ),
    WEEKNUM ( [Date] - 1, 2 ),
    IF ( [Date] > DATE ( 2023, 1, 1 ), WEEKNUM ( [Date], 2 ) - 1, [Weeknum] )
)

Hope that can help you.

Best Regards,

Community Support Team _Charlotte

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