Extracting an ID from a built up string?

I am building up a string a storing them in the database:

eg:


72-8442

I was wondering how I would go about extracting '8442' from this string in SQL because I would like to do:

select serialnumber from assets where id = '8442'

Any ideas?

The Format is always:

ID1-ID2
72-8442

Cheers