Instead of just Looping across the rows of the table, you can also Loop across the columns. Use the Column List Loop Start and Loop End (Column Append) nodes. Choose in the include list, all the columns you want to Loop across one at a time, those in the exclude list will be in every loop. Of course just before the Loop End (Column Append), you will need a column filter to remove these columns which were in the exclude list, otherwise you will have multiple copies of them at the end. You can get these excluded columns back by simply using the Joiner node after the Loop End.