Singleton design pattern in PHP

You can find all the information you need on the web if you google singleton design pattern. So I'm not gonna fill your head with all the theory.

I'll tell you how you can implement it.

How to fit an image in a rectangle area in PHP using GD

Have you ever had a fixed space in your design, and you must put an image that fits exactly there, while preserving the aspect ratio? Well, this is what i'll explain in this article.

Using a transparent PNG image as watermark in PHP

Sure there are plenty of scripts on the internet that does this thing ... but very few explain this.

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.