Add an "Active Record" column

Hello marktvc 

you can add a Group-function on your ID with 2 function. AllRows and MaxDate of your date-column.

After that expand your grouped table and check whether your date-column is the same as the MaxDate.

Here some code

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTIw1TMw0jMyUIrVgQgYG+gZGCMLGBnoGcJVOAEFDC3QBYAqDMACsQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [UNIQLIN = _t, INSERTDATE = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"UNIQLIN", type text}, {"INSERTDATE", type date}}, "de-DE"),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"UNIQLIN"}, {{"MaxDate", each List.Max([INSERTDATE]), type date}, {"AllRows", each _, type table [UNIQLIN=text, INSERTDATE=date]}}),
    #"Expanded AllRows" = Table.ExpandTableColumn(#"Grouped Rows", "AllRows", {"INSERTDATE"}, {"INSERTDATE"}),
    #"Added Custom" = Table.AddColumn(#"Expanded AllRows", "CURRENT_RECORD", each if [MaxDate]=[INSERTDATE] then "Y" else "N"),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"MaxDate"})
in
    #"Removed Columns"

transforms this

into this

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

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Kudoes are nice too

Have fun

Jimmy