you can create a range search using the following format for creating the recordset.
SELECT * FROM repsTable WHERE startZip <= paramZip AND endZip >= paramZip2
parameters:
name: paramZip
type: integer
default value -1
run time value: $_POST['enteredZIP']
name: paramZip2
type: integer
default value -1
run time value: $_POST['enteredZIP']