Subtracting one column from another column

Column 1 Column 2 Column 3
Email1 Email2
Email2 Email4
Email3
Email4
Email5

Hi guys, it’s an easy one but not for me. How can i populate column 3 with the emails from column 1 that are not present in column 2.
Kind regards

Answer 1

  • Lookup of column 1 (you get an array)
  • If-the-else column: if column 2 is included in lookup then true else ‘null’
  • Column 3: Create another If-then-else column. If ITE column (previously) is true then ‘null’ else column 1.

Something like that.

Answer 2

Your table does not follow normal form, I would redo it.

Column 1 Column 2
Email 1
Email 2 true
Email 3
Email 4 true
Email 5
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