Zip Code approximation

[Anon]

Does anyone have any idea how to do something like this

I have an application where a user can search for people that live near them with a drop down box

<select>
<option value="1">whithin 10 miles</option>
<option value="2">whithin 10-50 miles</option>
<option value="3">whithin 50-100 miles</option>
<option value="4">whithin 100-200 miles</option>
<option value="5">whithin 200-500 miles</option>
<option value="0">anywhere</option>

I want to do this by zip code approximation

For example I can choose all the people that live within 100-200 miles from me; so my script should calculate all the people in the database whos zip codes are within 100-200 miles of the user's zipcode who is executing the query

An example whould be like on match.com
Thanks

[SiteCubed_com]

You'd need to base it on numbers... each postcode needs to relate to every other post code. For example, if you have 3 states:

State1
State2
State3

then state1 is 10 miles from state2 and is 15 miles from state3. You would store it in a new table, like this

state | other_state | range

State1 State2 1

The range of 1 might b\mean 0-10 Miles, etc.... do you get the idea? Each state has to relate to every other state, so each state has 50 entries in the state table shown above...