PHP_SELF filter

[Jon12345]

I have a page displaying data from a mySQL db which I want to filter. So I figured I could have a button and a couple of fields at the top of my page:

1. Date

2. Category

I want to click submit, have the results filtered but on the same page. I know I need to use PHP_SELF filter and wildcards for when I don't enter anything into the fields. But has anyone got a simple example of this type of filter that I can refer to? I want to just filter a list of data that would appear below the filter fields and button.

Thanks,

Jon