Hierarchical select population jQuery/PHP

[Pammysue]

I have 3 select boxes in HTML, see this demo.What should happen: when one clicks on one of the options in the first \[code\]<select>\[/code\], data should be loaded into the second \[code\]<select>\[/code\] from a database. When one clicks on data in the second \[code\]<select>\[/code\], the third \[code\]<select>\[/code\] should be populated with further data from a database.Simple questionWhat is the best and easiest way to store and load the data in a hierarchical fashion. Like a tree view but with \[code\]<select>\[/code\] elements.