Dynamically Change Column Type based on Column Name/Type from another table

Thank you for your reply and the attached PBIX.

This is almost exactly what I need, with one change, in that the fChangeColumnsFromReference needs to have a second parameter to filter the ColumnMapping table by TableName.

The use case is the incoming column name(s) may all be the same across multiple tables, but the rename value is different. An example, using the sample provided:

In this case, there are 3 tables, each get imported with a column 'C', but the new name for 'C' on each table is different because the tables represent different things.

In your example PBIX, I adapted the ColumnMapping to include a TableName value, which represents which Table does that rename belong to. So far so good.

Then I edited the fChangeColumnsFromReference to include a second 'TableName' parameter. When invoking this function directly, it works correctly and I get the correct rename value depending on which TableName I specified. Still so far so good.

However the issue I have that I just can't seem to get my head around, is how to edit the Table query calling the function, to pass the TableName parameter in. I'm still trying to grasp how the function, which expects a parameter, doesn't have the parameter specified within the Table Query.

I'm assuming that in the TransformColumnNames function, it is effectively iterating over each column name and passing the column name to the fChangeColumnsFromReference function.

This is the only step that i'm now stuck on.

For whatever reason it's not letting me attach the revised PBIX, but here are the queries:

fChangeColumnsFromReference

(TableName as text, ColumnName as text) as text =>
  let
    Source =
      if (List.Contains(Record.FieldNames(#sections[Section1]), "ColumnMappingTest")) = true then
        ColumnMappingTest
      else
        null,
    ColumnNewName = try
        if List.Contains(Table.SelectRows(Source, each ([Table_Name] = TableName))[old], ColumnName) = true then
          if Text.Trim(Table.SelectRows(Table.SelectRows(Source, each ([Table_Name] = TableName)), each ([old] = ColumnName)){0}[new]) = "" then
            ColumnName
          else
            Table.SelectRows(Table.SelectRows(Source, each ([Table_Name] = TableName)), each ([old] = ColumnName)){0}[new]
        else
          ColumnName
    otherwise
      ColumnName
  in
    ColumnNewName

Example Table 3 (Country of Residence)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc6xCoQwDAbgd+ksR2096y64+QTFIdhydakQM/j4l0Q4ELnlzz98JInRjFAhgWm4IGbKKN07HyzPhBz0gWKWJpoJoa75QXulmDSSyt/Sea/EXZx1bc/zKMRZ8K/zvh3C663b8PpB6JzPbd1v1A2hs3IbDlIo15cv", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [C = _t, P = _t, S = _t, renameOther = _t, htasht = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"C", type text}, {"P", type text}, {"S", type number}}),
    RenameColumns = Table.TransformColumnNames( ChangedType, fChangeColumnsFromReferenceTest("Table3", each _) )
in
    RenameColumns