Power Query – how to reference ALL columns in a table? The Table.ColumnNames function

In Power Query, sometimes we need to do some change for ALL columns in a table.

But we don’t want to address them one by one, for two reasons:

• It can be unnecessarily lengthy
• The columns may vary in time

If we want, for example, in this table:

fill down all empty cells, we don´t have to write this:

• Source = Excel.CurrentWorkbook(){[Name=”Table1″]}[Content],
  #”Filled Down” = Table.FillDown(Source,{“Blue”, “Red”, “Grey”})

we can use this:

• Source = Excel.CurrentWorkbook(){[Name=”Table1″]}[Content],
  #”Filled Down” = Table.FillDown(Source,Table.ColumnNames(Source))

The typical use of Table.ColumnNames is for expanding columns from merged tables.