Free US ZIP Code Database as CSV

The census will generate that database for you:

Go to http://factfinder.census.gov/servlet/DCGeoSelectServlet?ds_n...

Click "All 5-Digit ZIP Code Tabulation Areas"

Click "GO"

Click "P1. Total Population"

Click "Add"

Click "Next"

Click "Start Download"

Download the database I posted in my other comment here, and try this SQL statement:

   SELECT z.ZIPcode, (sqrt((z.latitude-z2.latitude)*(z.latitude-z2.latitude)+(z.longtitude-z2.longtitude)*(z.longtitude-z2.longtitude)))) AS dist
   FROM `zip` AS `z`, `zip` AS `z2`
   WHERE `z2`.`ZIPcode = 'YOURZIPCODE'
   ORDER BY dist LIMIT 10

Might be faster if you do a query to get the lat and long for the ZIP code you need first, though. Hell, it would probably be fastest to skip the database all together and just import the data and loop the distance formula, recording the smallest distances as you go.

mySQL 'SELECT zip FROM '.insert table here.' WHERE (POW((69.1(tablelongitude-"'.$obj->longitude.'")cos('.$obj->latitude.'/57.3)),"2")+POW((69.1(tablelatitude-"'.$obj->latitude.'")),"2"))http://mybandsupport.com. You can see the result by entering the zipcode in the splash screen and clicking search. The function takes your zip, gets the long and lat, then the DB compares it to every zip's (4500) long and lat to find every zip within 20 miles.

Just a note: comparing every zip code and its distance and recording the distance to a DB would create upwards of 12 million records. This might be the breaking point for some.... I was thinking about doing it myself. Once I worked out the numbers I backed away.

If you know the origin and destination long and lat this works well to calc distance. $dist = sin(deg2rad($this->lat1)) * sin(deg2rad($this->lat2)) + cos(deg2rad($this->lat1)) * cos(deg2rad($this->lat2)) * cos(deg2rad($theta));