Working with U.S. Zip Codes

I am currently working on an application (to be run under an ORACLE7 database) which requires me to find the state for a specific U.S. zip code.

I've already downloaded a list of all U.S. zip codes from a web site and have stored it in a base table. The list has over 33,000 entries of zip codes, cities, and states. But rather than having to search the entire table each time, I'm wondering if anyone is aware of a more optimal solution for such task.

I was told by someone that using the first 3 digits of the zip code, one could find the state in which the zip code resides. Is this actually true? If it is, this would probably reduce the list to < 1,000 entries.

I would appreciate any help on this from anyone doing a similar task.

Thanks.
-- Kevin Received on Sun Apr 21 1996 - 00:00:00 CEST