Is this possible?

Using PHP 404pl1 / MySQL 3.23.35 / PWS / W98SE if anybody should need to know... The stuff is for an intranet application. 1: To execute php code when a A HREF link is clicked. I have the need to change a session variable depending on which link (of a couple) that is clicked. The link is supposed to call $PHP_SELF which then change its output depending on the value of the session variable. I know that i can solve it by letting the link call different php scripts - which update the session variable and then call back to the first page. If there is another way ( javascript maybe?), i am interested to know about it. 2: To have one undo step on a database update. Do anybody know / seen any example / tutorial on how this kind of function can be implemented? Let me know! I have read most of the stuff at Newbie network, PHPdeveloper, PHPeverywhere, Zend, Devshed, Webmonkey and PHPbuilder - but i have never come across anything like this. -- Michel Laine