Hi all, but of a problem here.
I'm using a drop down list, and want to call a function when the user selects a value.

"function($variable_here) {
bits and bobs here
}
<form name='select_user'><select name='user' onChange='function(user.value)'> <option>Select User</option><option value='1'>Admin</option></select></form>"

I'm using PHP to do the function bits and bobs, but can't get it to call the function and process the data

You can't call a PHP Function directly from the onChange event of a drop down list like that. (PHP happens server side, before the page is sent to the client, the onChange event happens on the client side, the server has already sent the page and isn't worrying about it any more.)

You have two options, depending on what it is you want to do. You could write the function in JavaScript, but bear in mind if you're doing authintication orientated things it won't be very secure.

Your other option is to write a small JavaScript function to refresh the page and add the value as a query string (or form value), then in the PHP script, check to see if that value exists, then execute the code from there.

I can't give you a full working example because I don't do PHP.

Look's like I'll have to do the second option, as I want to load data from a database (MySQL) when a user selects a client from the list.

How can I get the browser to automatically select the option that the user selected, after the page has been refreshed?
(ie, the user selects, eg the 3rd option; then the page refreshes, what code do I need for the browser to re-select the 3rd option)?

When I used Visual Basic, you ran a line of code something along the lines of "List1.ListIndex = 3". Is there something similar in HTML, perhaps users.listindex = "3"?

Don't worry, I've used a script in PHP to select the id, by using entering "selected" into the <option> header if the id matches that of the submitted one.