VLookup in the same table

Hi Magnus-CPH-DK ,

According to your description, here's my solution.

Add a custom column.

if Table.RowCount(Table.SelectRows(#"Changed Type",(x)=>x[Kontrolnummer]=[Forudgående Kontrolnummer]))=0 then null else Table.SelectRows(#"Changed Type",(x)=>x[Kontrolnummer]=[Forudgående Kontrolnummer]){0}[Kontrolnummer_Type]

Get the correct result.

Here's the whole M syntax:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlbSUTJ2BBJKsTrRSqZAhimcZwZkmMF55kCGOYhnAuZaAFkWLiAxMNcSyLJEcA0NgExDA6hALAA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Kontrolnummer = _t, Kontrolnummer_Type = _t, #"Forudgående Kontrolnummer" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Kontrolnummer", Int64.Type}, {"Kontrolnummer_Type", type text}, {"Forudgående Kontrolnummer", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each if Table.RowCount(Table.SelectRows(#"Changed Type",(x)=>x[Kontrolnummer]=[Forudgående Kontrolnummer]))=0 then null else Table.SelectRows(#"Changed Type",(x)=>x[Kontrolnummer]=[Forudgående Kontrolnummer]){0}[Kontrolnummer_Type])
in
    #"Added Custom"

I attach my sample below for your reference.

Best Regards,
Community Support Team _ kalyj

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