multiple primary keys

[Vuillemot, Ward W]

I have a question regarding multiple primary keys. Do all DBs handle multple
primary keys?  In addition, can only one of the primary keys be
autoincremented?
I am curious how this pertains to mySQL where we have:
        $sth->{'mysql_insertid'};

Is there a way to determine the name of column that was autoincremented?
Easily, that is. . . .ie, a simple command such
        $sth->{'hashValueHere'};

Thanks,
Ward