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hymieho's avatar
hymieho
Icon for Resolver I rankResolver I
8 years ago
Solved

Combine multiple CSV files, then add IsLatest column based on date in filename in Power Query / M

I am importing a series of CSV file and they all have a date in the file name.  Ex:

 

2017-09-26.CSV

2017-10-23.CSV

etc.

 

I am able to combine them and create a date column based on the filename. Now I would like to add a column called [IsLatest, determine which is the most recent date, and have Yes or No in the column accordingly. I can do this in DAX with a custom column, but I wanted to stretch my M skills but I just can't figure it out. Any Power Query / M gurus who can point me in the right direction?

Need Help

2 Replies

  • v-jiascu-msft's avatar
    v-jiascu-msft
    Icon for Microsoft Employee rankMicrosoft Employee
    8 years ago

    Hi hymieho,

     

    You can try a custom column like this:

    List.Max(#"Changed Type"[Column1])

    Combine_multiple_CSV_files

     

    Best Regards,

    Dale

    • hymieho's avatar
      hymieho
      Icon for Resolver I rankResolver I
      8 years ago

      Works like a charm--thanks for the tip!

       

      1. Add a (temporary) custom column as you mentioned with the List.Max(date)

      2. Add a 2nd custom column that checks to see if [Date] = [Latest Date in group]

      3. Remove the temp column

       

      #"Added Conditional Column" = Table.AddColumn(#"Added Custom", "IsLatest", each if [Add Column with latest date] = [Date] then "Yes" else "No"),
      #"Renamed Columns2" = Table.RenameColumns(#"Added Conditional Column",{{"Add Column with latest date", "Latest Date in group"}}),
      #"Removed Columns1" = Table.RemoveColumns(#"Renamed Columns2",{"Latest Date in group"})