IF Statements for Strings in Column Expressions

Hi - I want to say

IF left( code , 4 = “DRAM” then “RKW”

ELSEIF left( code ,4 - “DRAQ” then “AQ”

ELSE “UNK” ENDIF

I have tried quite a few of the suggestions here (==, encasing them in $ signs, using curly brackets, etc.) to accomplish this and keep failing. Are strings not an option in Column Expressions? Or am I missing something obvious?

If it can’t be done in Column Expressions is there somewhere it can be done so a node for each individual one is not necessary? Thanks.