Need to place html code on dynamic pages- PHP help

I need to place three set HTML advertisement codes in

mydomain/index.php,
mydomain/index.php?tag=funny+videos,
mydomain/index.php?tag=music+videos


But I have only the index.php file. Where to place the code for mydomain/index.php?tag=funny+videos and mydomain/index.php?tag=music+videos

Please help me!!

 

all are going to the same file and so the index.php will need to include conditional logic (ie if tag=funny+videos then .... else if tag=music+videos then .... else .....)

This can be directly in the file or can be in a separate file pulled in with an include if your using PHP, ASP etc or a shared class if in .Net

 

But "tag" is not a declared variable. then how can I declare conditional logic (ie if tag=funny+videos then .... else if tag=music+videos then .... else .....)

 

Thanks Astarothsolutions . I got it!!

 

NP - couldnt give a code example as we use .Net rather than PHP