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Anders_G's avatar
Anders_G
Icon for Helper I rankHelper I
3 years ago
Solved

Help with Date_request in Date.IsInPreviousNMonths

Hi,

 

I'm trying to manage my data imports with date filters. I want to import X months in the past from the previous year. I've read you can change the date_request in the Date.IsInPreviousNMonths([date_request], 2) function.

 

I've tried creating a custom date query from a blank query and giving it today's date one year in the past. I've named the query Datefilter.

 

My custom function then looks like this.

= Table.SelectRows(Dataset_(LY)_View, each Date.IsInPreviousNMonths(Datefilter, 2))

 

However, it doesn't return any data. What am I doing wrong?

Need Help
  • v-yueyunzh-msft's avatar
    v-yueyunzh-msft
    3 years ago

    Hi , Anders_G 

    Accoding to your description, you want to filter the previous N months od the last year. Right?

    I mean this , you can put this in "Advanced Editor" in Power Query Editor:

    let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Tc3BDQAhCETRXjib4ODqQi3G/ttYJJrl+vIzMydJFWEwqBBolQsu3UnkGsLGtpbQGLoNTwrrCZEsHsYPnc3h1SOw2HfS5lPrAw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, value = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"value", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", (x)=>if Duration.Days(Date.AddDays(Date.From(Date.From(DateTime.LocalNow())),-365)-x[Date]) >=0 and  Duration.Days(Date.AddDays(Date.From(Date.From(DateTime.LocalNow())),-365)-x[Date]) <=60  then 1 else -1          )
in
    #"Added Custom"

    The table is like this:

    Then we can filter the [Custom]=1 then we will meet your need .

     

    Best Regards,

    Aniya Zhang

    If this post helps, then please consider Accept it as the solution to help the other members find it more quickly

     

     

4 Replies

  • Rickmaurinus's avatar
    Rickmaurinus
    Icon for Helper V rankHelper V
    2 years ago

    Hi there,

     

    The Date.IsInPreviousNMonths function tests whether a date value is within the specified number of months, compared from your current system time. 

     

    For your filter to work,  you should change around the 'DateFilter' variable, to a date column that's actually within your query. For instance, if you have a [Sales Date] column you could use: 

    Table.SelectRows(Dataset_(LY)_View, each Date.IsInPreviousNMonths([Sales Date], 2))

     

    More details here: https://powerquery.how/date-isinpreviousnmonths

     

    However, if you want to filter on dates starting from last year, you would need something like: 

     

    Table.SelectRows( 
  Dataset_(LY)_View, 
  each [Sales Data] < Date.AddYears( Date.From( DateTime.LocalNow() ), -1 )
    and [Sales Data] >= Date.AddMonths( Date.From( DateTime.LocalNow() ), -14 )
)

      

    In that way you filter your data down to the relevant dates. 

     

    --------------------------------------------------

    @ me in replies or I'll lose your thread

     

    Master Power Query M? -> https://powerquery.how

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    If this post helps, then please consider accepting it as the solution to help other members find it more quickly.

  • v-yueyunzh-msft's avatar
    v-yueyunzh-msft
    Icon for Community Support rankCommunity Support
    3 years ago

    Hi , Anders_G 

    The "Date.IsInPreviousNMonths" function is automatically compared with the current time of the system, and the comparison date cannot be customized.

    For more information, you can refer to:
    Date.IsInPreviousNMonths - PowerQuery M | Microsoft Learn

     

    If you want to  import X months in the past from the previous year .  I think you need to calculate the days between two days and then compare the days to filter your table.

     

    Best Regards,

    Aniya Zhang

    If this post helps, then please consider Accept it as the solution to help the other members find it more quickly

     

    • Anders_G's avatar
      Anders_G
      Icon for Helper I rankHelper I
      3 years ago

      Thank you for the clarification.

       

      If you want to  import X months in the past from the previous year .  I think you need to calculate the days between two days and then compare the days to filter your table.

      I would be very grateful if you could explain the process in more detail. I have no real knowledge of M or SQL. I mostly copy and paste what I can find on this forum. 

      • v-yueyunzh-msft's avatar
        v-yueyunzh-msft
        Icon for Community Support rankCommunity Support
        3 years ago

        Hi , Anders_G 

        Accoding to your description, you want to filter the previous N months od the last year. Right?

        I mean this , you can put this in "Advanced Editor" in Power Query Editor:

        let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Tc3BDQAhCETRXjib4ODqQi3G/ttYJJrl+vIzMydJFWEwqBBolQsu3UnkGsLGtpbQGLoNTwrrCZEsHsYPnc3h1SOw2HfS5lPrAw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, value = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"value", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", (x)=>if Duration.Days(Date.AddDays(Date.From(Date.From(DateTime.LocalNow())),-365)-x[Date]) >=0 and  Duration.Days(Date.AddDays(Date.From(Date.From(DateTime.LocalNow())),-365)-x[Date]) <=60  then 1 else -1          )
in
    #"Added Custom"

        The table is like this:

        Then we can filter the [Custom]=1 then we will meet your need .

         

        Best Regards,

        Aniya Zhang

        If this post helps, then please consider Accept it as the solution to help the other members find it more quickly