Building a Simple Search Engine with PHP

"A little while ago, I was working on an intranet site for a mid-sized company. As the site grew in both size and popularity, the assigner requested me to extend the site with a search feature. Since one of the rules of the intranet was that all logic code should be written in-house, using an existing open source engine was not an option

Within a day, the engine was quite complete, and the result actually turned out better than expected. With PHP, MySQL, and a few techniques, these small projects are very easy. This article presents a cut-down version of the search engine. I hope this will encourage you to develop an engine that suits your particular needs, with the exact features you desire."

http://www.onlamp.com/pub/a/php/2002/10/24/simplesearchengine.html