$_SERVER['PHP_SELF'];???

[eluser]husni[/eluser]
hey guys..can i use

Code:

$SERVER_['PHP_SELF'];

in my application..
i want to execute something in same page..
where i should put the code? view or controller file??
and how to do it..

i need to display all the list of report and before that i must choose the options which category i want to search..