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asjones's avatar
asjones
Icon for Helper V rankHelper V
5 years ago
Solved

Max Date Math Issues In Power Query

I wrote an Excel formula that I would like to convert ot Power Querey, but  I cant get the List.Max or Table.Max to work thust the rest fails also. I want a new column that works simular to this exc...
Need Help
  • v-kelly-msft's avatar
    v-kelly-msft
    5 years ago

    Hi asjones，

     

    Since you need 2 columns based on the max date,I would suggest you first create a column to get the max date,using below M codes:

    =Table.Max(#"Changed Type","Date")

    Then create another 2 columns to get 7days and 14days:

    =if [Date]>Date.AddDays([Max date.Date],-7) then "7 days" else null
    =if [Date]>Date.AddDays([Max date.Date],-14) then "14 days" else null

    And you will see:

    For the related .pbix file,pls see attached.

     

    Best Regards,
    Kelly

    Did I answer your question? Mark my reply as a solution!

Anonymous's avatar
Anonymous
Not applicable
5 years ago

Here's a way that'll work nice and fast. Let's say your current final step is named LastStep.  Just add a new step named MaxDate7. Then in the Formula Bar, type:

= Date.AddDays(List.Max(List.Buffer(LastStep[Dates])),-7)

 

Then add your column; add a new step named "NewColumn", then in the formula bar, type:

= Table.AddColumn(LastStep, "DateCompare", each if [Date] > MaxDate7 then "7 Days" else "-", type text)

 

This way your Max Date-7 days is computed once and stored as a variable. Having it in the in statement will cause you trouble. If you want to add the Date-14 variable, just add another step before you add your columns named MaxDate14, and that would be:

= Date.AddDays(MaxDate7, -7)

 

--Nate

 

edhans's avatar
edhans
Icon for Community Champion rankCommunity Champion
5 years ago

Just be careful with List.Buffer on a large list. Put a few hundred thousand or million records in it, and it could cause Power Query to consume all RAM on the PC. I thought about doing it that way, but I still contend Power Query isn't the right place for this unless you know it is going to be a relatively small dataset.