Daniel,
Sure we don't know what the interviewer was thinking, but this the type of
question that one might use to dig for experience and problem solving. It
is likely the sequence question alone is fairly simple and straightforward
(one would hope), but by combining it with this "odd" behavior (Hmm, got 2
rows back from dual.) The interviewer is asking both about sequences, what
dual is, and why might it be acting unusual.(have 2 rows) It is the type of
thing that would happen in real life (some bozo did an insert into dual and
now it has 2 rows, and is creating all sorts of havoc.)
Jim
"DA Morgan" <damorgan_at_exesolutions.com> wrote in message
news:3E4FD982.EDE9B0B0_at_exesolutions.com...
> Jim Kennedy wrote:
>
> > I think the question was aimed at finding out that someone had added a
row
> > to dual and that will cause problems with applications that use dual
> > expecting 1 row.
> > Jim
> >
> > --
> > Replace part of the email address: kennedy-down_with_spammers_at_attbi.com
> > with family. Remove the negative part, keep the minus sign. You can
figure
> > it out.
> > <Kenneth Koenraadt> wrote in message
> > news:3e4f8b9d.629164_at_news.inet.tele.dk...
> > > On Sat, 15 Feb 2003 18:17:04 GMT, "Ryan" <rgaffuri_at_cox.net> wrote:
> > >
> > > >I got a trick question in an interview and I dont know if what I said
was
> > > >write. It was a written exam so I couldnt ask.
> > > >
> > > >Someone does
> > > >
> > > >select sequence.nextval
> > > > from dual;
> > > >
> > > >you get two sequence numbers back. All I could think of was that
someone
> > > >inserted a second row into dual.
> > > >
> > > >Could any other reason lead to two sequence numbers being returned?
> > > >
> > > >
> > >
> > > Hi Ryan,
> > >
> > > Maybe the question was just awkwardly asked. I guess they wanted to
> > > test if you knew about both sequence.NEXTVAL and sequence.CURRVAL :
> > >
> > > Nextval is returned from the statement. No doubt. And if you
> > > afterwards do :
> > >
> > > select sequence.currval from dual;
> > >
> > > You get the same value again. In that sense, you can say that you get
> > > 2 values at your service, *because* :
> > >
> > > If you start a user session and have a sequence myseq and issue :
> > >
> > > select myseq.currval from dual;
> > >
> > > You get ORA-08002: Sequence MYSEQ.CURRVAL not yet defined.....
> > >
> > > You have to invoke NEXTVAL by *first* calling
> > >
> > > select myseq.nextval from dual;
> > >
> > > and *then* you can do ;
> > >
> > > select myseq.currval from dual;
> > >
> > > So "select sequence.nextval from dual" does, make another value
> > > avilable : sequence.currval.
> > >
> > > Interviewers trying to make tricky questions, are often tricking
> > > themselves instead....
> > >
> > > - Kenneth Koenraadt
> > >
> > >
> > >
>
> As opposed to SELECT COUNT(*) FROM dual;?
>
> The question is reasonable as a way of understanding someone's
understanding of
> dual and how sequences work. Trying to psychoanalyze those that put
together the
> questions may not lead to a lot of clarity as we'll likely never know why
any
> question ends up on one of these things.
>
> What I find more amazing is the questions and answers (especially on the
OCP)
> that are clearly incorrect.
>
> Daniel Morgan
>
Received on Sun Feb 16 2003 - 13:06:26 CST
