Concatenate column with condition Recursive way or any other option?

Hello SaaM 

 

not to 100% clear how your column is calculated. I hope I guessed right.

Try to add a new column with this formula. The variable PreviousStep has to refer to your prior step

if [column]>[index] then Text.Combine(Table.SelectRows(PreviousStep, (sel)=> sel[Item] = [Item] and sel[column]>= [column])[Serial number], "-")
 else [Serial number]

here a complete example

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTIGYiMgVorVgQiYQAUNQeDQAri4KVTOCARQREHYGATAok4gdYaGYNIAZjBI0MzUxBguZ4QuDKUgZjiD7DeAE87OzkqxsQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Item = _t, column = _t, index = _t, #"Serial number" = _t]),
    #"Replaced Value" = Table.ReplaceValue(Source,"",null,Replacer.ReplaceValue,Table.ColumnNames(Source)),
    PreviousStep = Table.TransformColumnTypes(#"Replaced Value",{{"Item", type text}, {"column", Int64.Type}, {"index", Int64.Type}, {"Serial number", type text}}),
    AddConcatenateSerial = Table.AddColumn(PreviousStep, "Concatenate Serial Numbers", each if [column]>[index] then Text.Combine(Table.SelectRows(PreviousStep, (sel)=> sel[Item] = [Item] and sel[column]>= [column])[Serial number], "-")
 else [Serial number])
in
    AddConcatenateSerial

this 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

Hi,

 

This should do the trick:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUTIGYiMgVlCK1YGImEBFFQxBACFuCpUzAgEUURA2BgGwqBNInaEhmDSAmwwSNTM1MYZLGqELQymIIc5AFlg3hHB2dlaKjQUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Item = _t, column = _t, index = _t, #"Serial number" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Item", type text}, {"column", Int64.Type}, {"index", Int64.Type}, {"Serial number", type text}}),
    fn = (tbl as table,colval as text) => Text.Combine( Table.SelectRows(tbl, each [Item] = colval)[Serial number], "-"),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each if [column] > [index] then fn(#"Changed Type", [Item]) else 0
)
in
    #"Added Custom"

Kind regards, Steve