Problem with the group statement...

From: Volker Hetzer <volker.hetzer_at_ieee.org>
Date: Mon, 15 Jul 2002 21:30:52 +0200
Message-ID: <agv7tc$md1$1@dackel.pdb.sbs.de>

Hi!
I have trouble understanding the group statement. Here is a small example:

create temporary table x (a int, b int);

insert into x values(1,1);
insert into x values(1,2);
insert into x values(1,3);
insert into x values(2,1);
insert into x values(2,2);
insert into x values(2,3);
insert into x values(3,1);
insert into x values(3,2);
insert into x values(3,3);

select * from x group by a;

Now, this gives me:
a b
1 1
2 1
3 1

However, I had expected it to give the whole table. The "Introduction to database systems" says: "... by (conceptually) rearranging it [the table] into the minimum number of groups such thaqt within any one group all rows have the same value for the combination of columns identified by the GROUP BY clause."

Well, I specified only a in the group by clause and I think, there's nothing to prevent theselect statement to put three rows in a group. Obviously, my thinking is faulty but I'd really like to know where.

Greetings and thanks!
Volker Received on Mon Jul 15 2002 - 14:30:52 CDT