mysql.so - where can I get it?

[Lembit M]

Hello,
I am needing the mysql.so for Linux but do not know how to get/install it.

I am a newbie to Linux, but have installed worked with Apache, MySQL and PHP on Windows, no problem there!

My uname -a is
Linux melb_linux 2.6.5-1.358 #1 Sat May 8 09:04:50 EDT 2004 i686 i686 i386 GNU/Linux

and my php -v is

PHP 4.3.8 (cgi) (built: Jul 16 2004 09:23:33)
Copyright (c) 1997-2004 The PHP Group
Zend Engine v1.3.0, Copyright (c) 1998-2004 Zend Technologies

I have Apache2 running fine with php but lack the mysql.so extension to correctly refer to. It does not exist anywhere on the system.
How/where do I exactly get this mysql.so ?

Compiling source stuff puts fear into me but have tried but no mysql.so gets produced anywhere and I am not sure what I am doing wrong.

In a naive way, I have tried all sorts of rpm -i stuff with no joy and spent many hours googling looking to wheer I could download this one file.

Can anyone assist of provide me with that file?
What further info could I provide for you so that I could get the right mysql.so file?

thank you