help with conditional copy %track% to %discnumber%

here's what i'm trying to accomplish:

if %track% contains "-" then i want to copy %track% to %discnumber%

for example, many tracks are numbered like this:
1-01
1-02
1-03
etc...

any help would be greatly appreciated, i'm sure this is simple, i'm just having trouble figuring it out on my own. thanks

i seem to have accomplished it with with the following "guess value action"

Source format
%track%

Guessing pattern
%discnumber%-%track%

alternative methods to accomplish it still welcome

Do you really want to copy the whole of TRACK into DISCNUMBER? Or just the leading "1"?
Anyway: it would be easiest to apply a filter like
%track% HAS "-"
If you then want to split the field then an action of the type "Import tag-field (guess values)" for TRACK and the mask
%discnumber%-%track%
would move the 1 (or any other number in front of the hyphen) to DISCNUMBER.

If you only want to copy then run a simple "Format tag-field" action for DISCNUMBER with the format string %track%

well, yes, just the leading "1", but for simplicity i figured i could clean it up after the copy using "replace with regular expression"