Background: We live in a small state and have 10 "stores" located throughout it. Each of these stores has their own WordPress Page. We have a master list of ZIP codes for our state (roughly 400 ZIP codes) and would like to assign these ZIP codes to one of the 10 WordPress Pages. If a user enters their ZIP code in a search field, we'd like to take them directly to the assigned "store" WordPress Page.
What's the best way to go about building this while keeping WordPress' best practices in mind? It's a pretty simple one-to-many relationship (Page -> ZIP codes) and I don't think any geocoding is needed, but I'm not an expert on building WordPress plugins and want to do things correctly.
I'm thinking a simple database table of the 400 ZIP codes with a "post_id" field corresponding to the correct WordPress page, but it would be nice to have some sort of interface on the backend that allows us to bulk-assign ZIP codes (via a multi-select box?) to a WordPress Page without having to edit each database row manually - are there any tools to help build these interfaces or is this something I'll have to create manually?