PHP Store Locator

[newyorkcityzoo]

A Client's website that I'm working on has a php script (by someone else) that finds locations within 50 miles for the entered zip code.  The zip code database is rather old and does not have all the current zip codes.  So when a user enters an unlisted zip they receive zero results.  I need to update the database so it contains all current zips and am willing to pay for good data.  The issue is finding a database that will work with the code all ready in place.  I have looked at a bunch of sample data set from zip code database vendors and they do not have the same data types.  My current zip database looks like this:

 

Table Name: zip_code

 

zip_code    latitude    longitude    rad_lat    rad_lon

35004        33.6064    -86.5025    0.586542  -1.50975

 

My questions:

 

Does anyone know where this data came from? 

Where can I find an updated version of this zip data? 

What do rad_lat and rad lon stand for?

Can I get rad_lat and rad_lon using some sort of equation?

 

Thanks

 

 

 

 

 

 

[xylex]

rad_lat/rad_lon are radian equivalents of the latitude/longitude degree measurements.

 

radians = (degrees * pi)/180

[newyorkcityzoo]

Thanks xylex, solved my problem.