Question about combination PRIMARY keys and INDEX

[Daevid Vincent]

If I have a table with a primary key like this:

CREATE TABLE `answers` (
`qid` INT UNSIGNED NOT NULL ,
`userid` INT UNSIGNED NOT NULL ,
`groupid` INT UNSIGNED NOT NULL ,
`comments` TEXT NOT NULL ,
 PRIMARY ( `qid` , `userid` , `groupid` ) 
);

But I will also be searching in various pages, for all 'answers' from a
certain userid or say that belong to a certain groupid, do I still need to
create separate INDEXes for those fields, or is it enough to have them in
that combination PRIMARY key?