I have a form field for zipcode in US. My problem is that sometimes people tend to put in the post box number after the zip code, like 12345-4444. I'm using the first 5 digits to compare it with a zip code database i have here and then send the user to a particular page. How can I just read the first 5 digits of the zip code field and then compare it with a table in the DB and construct a query? I'm not sure if I'm clear enough.