Format date of column headers after pivoting

[freelensia]

I have a table with country, date, and a value column. I want to pivot the date column so that I can see the value progressing over each day (each row in the table is a Monday of the week).

let
    Source = AdvWeeklyStats,
    DelCol = Table.RemoveColumns(Source,{"New infections", "New deaths", "Total deaths", "Day of Week"}),
    SortByDate = Table.Sort(DelCol,{{"Date", Order.Ascending}, {"Country", Order.Ascending}}),
    PivotCol = Table.Pivot(Table.TransformColumnTypes(SortByDate, {{"Date", type text}}, "en-US"), List.Distinct(Table.TransformColumnTypes(SortByDate, {{"Date", type text}}, "en-US")[Date]), "Date", "Total infections")
in
    PivotCol

However after pivoting my date column headers are displayed in m-d-yyyy format.

How can I display them in yyyy/m format? Keeping in mind I do not want a monthly aggregate ! Each record must still pivot to its own column, and there should be 4 columns for each month like this:

2020/3 2020/3 2020/3 2020/3 2020/4 2020/4 2020/4 2020/4 2020/5 ...

If I change en-US to ja-JP then I get the dates formatted as yyyy/mm/dd which is a good start, but not what I need. I looked at this thread but the inner function was too complicated for me to replicate in my case.

Can anybody help me?
@Jimmy801 @Greg_Deckler @amitchandak @parry2k @Mariusz @ImkeF 

[Jimmy801 · Accepted solution]

Hello @freelensia 

column headers have to be unique. So why not using weeks instead of months? Here an example

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("TczBDcAgDEPRXXxGyEkoPXeH3lD2XwNQq4Sb9WT9MfC8KKBWWlWuKfDyq/RQTVULtVRjaEvlKrRPr6NrW2VrP7qM7w33CQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Country = _t, Date = _t, Value = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Country", type text}, {"Date", type date}, {"Value", Int64.Type}}, "de-DE"),
    #"Calculated Week of Year" = Table.TransformColumns(#"Changed Type",{{"Date", each Text.From(Date.WeekOfYear(_))&"/"&Text.From(Date.Year(_)), type text}}),
    #"Pivoted Column" = Table.Pivot(#"Calculated Week of Year", List.Distinct(#"Calculated Week of Year"[Date]), "Date", "Value", List.Sum)
in
    #"Pivoted Column"

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Have fun

Jimmy