Calculate the distance using lattitude, longitude and ZIP codes in MySQL

So, assuming we have a table:

ZIP_CODES
zip_code | lattitude | longitude

We take this zip code from NY
$zip = 10001
$lat = 40.750742
$lon =-74.52976

What we need is the Earth radius (6371 km).

If we need to search the zip codes that are in a 10 km area, we could use this 'small' sintax:

How to calculate age in MySQL

When programming, you hit yourself with many problems, that apparently are very simple, but require a rather difficult syntax.

On a site, i found a small problem - to calculate the age of the person and see if that person is between 2 selected ages.