I have a question on a practice assignment that I can't solve. Can someone
help me out?
Question:
The table Arc(x,y) currently has the following tuples (note there are
duplicates): (1,2), (1,2), (2,3), (3,4), (3,4), (4,1), (4,1), (4,1), (4,2).
Compute the result of the query:
SELECT a1.x, a2.y, COUNT(*)
FROM Arc a1, Arc a2
WHERE a1.y = a2.x
GROUP BY a1.x, a2.y;
Which of the following tuples is in the result?
a) (2,3,2)
b) (2,4,6)
c) (4,2,6)
d) (3,2,6) 4 1174
KGuy wrote: I have a question on a practice assignment that I can't solve. Can someone help me out?
Yes, create the table in question to your database, insert the given
values to there and then execute the given query and check which of
given results matches to the actual result.
This task is so simple that you don't even need brains to solve it,
since all you have to do is follow the instructions, compare few rows
and tell what you see.
If you don't have database, you can get one for free, for example mysql: http://www.mysql.com/
> Yes, create the table in question to your database, insert the given values to there and then execute the given query and check which of given results matches to the actual result.
Of course, I could do that, but I would like to understand why the output is
what it is. Sorry if I was unclear. Thanks for the reply.
-Imran
KGuy wrote: Of course, I could do that
Don't say you could do that, just do it. When you tell the corrent
answer, someone might be able explain it. And if want to make a guess,
be sure not choose wrong one.
Please understand that if we just give the correct answers it would be
the same as just shooting you in the head. It would do you more harm
than good. Point of practise assignments is that you learn by doing them.
>I have a question on a practice assignment that I can't solve. Can someone help me out?
Thanks everybody. I managed to solve it by hand using tips from someone
(Andy Hassall). It takes a while, but at least it's doable and I understand
it. If the answer is important to you, reply to this post. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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