Querying the Database

[Reven]

I've not written a script yet, as I don't know where to start with this. I can do all the querying stuff fine in PHP, but the problem I have is where to put the actual PHP code that queries stuff from the database. It will include the vB template, so I'll have all the usual global.php stuff and navbars etc.

Basically, do the custom query codes have to go within a [do] function, like this:

PHP Code:

if ($_REQUEST['do'] == "blah blah")
{
do certain query;
} 


Do they go somewhere else, such as a template bit (I've found one called 'PHP Include Templates', is this where I assign variables to my queries?), or do they have to be embedded in the actual php file?

Sorry if this is confusing.

NB. I've not yet upgraded my board to 3.5.0 RC X from 3.0.8, we're waiting for the Gold version, but I've read about Hooks and Plugins - does this allow you to specify custom PHP code and have it called from a custom php file?