RegEx - Replacement Text Equals Another Column's Cell Value

[ddavis216]

I am using the RegEx Replacement tool to strip out a leading "9999" and replace it with the value in another column, in this case the column is called [FileName] which has two rows, each cell containing the same number. Instead the tool is simply replacing the "9999" with "[FileName]".

Can someone please explain how I might be able to solve?

 

[roadhouse · Accepted solution]

Might be easier in the Formula tool to use the regex replace function.

It would look something like this: regex_replace(field_name,"pattern",[replacement])