Formula for Null cells

[CMCesar]

Hey Alteryx Community, got a question for a formula. I have a column (we'll call it column A) with lets say 40%null and 60% ok. I want to put a formula that takes other info from that line to fill in the Null such as ( [column B]+"-"+[column C] ). But I want the formula to only affect the Null cells in column A and not the Ok ones. Any idea how to write out the logic? 

[DataNath]

In your example, you would use the following:

IF ISNULL([Column A]) THEN [Column B]+'-'+[Column C]

ELSE [Column A]

ENDIF

All this is saying is: If column A is null, fill it with your B+C, otherwise leave it as is.

Due to the size constraints of updating an existing column, you may need to put a select tool before it and bump up the 'Size' to stop the field from being truncated if that's happening.