From: | Sébastien Meudec <seb(at)jack(dot)fr> |
---|---|
To: | <pgsql-sql(at)postgresql(dot)org> |
Subject: | get only rows for latest version of contents |
Date: | 2007-10-24 09:29:53 |
Message-ID: | 20071024092414.F2D721C000C4@mwinf2027.orange.fr |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
Hi everybody.
I have a table like that (i simplified it):
CREATE TABLE business {
idnode integer not null,
version_no integer,
c1 text,
c2 text,
c3 text
}
With a unique index in (idnode,version_no).
This table records many version from contents identified by idnode where
texts may be different.
So i can have:
Idnode | version_no | c1 | c2 | c3
111 | 2 | foo1 | foo2 | foo3
111 | 1 | fee1 | foo2 | foo3
111 | null | fee1 | fee2 | fee3
222 | null | too1 | too2 | too3
333 | 1 | xoo1 | xoo2 | xoo3
333 | null | yoo1 | yoo2 | yee3
I want to select all columns but only for last (greatest) version of each
content. So I want a result like:
Idnode | version_no | c1 | c2 | c3
111 | 2 | foo1 | foo2 | foo3
222 | null | too1 | too2 | too3
333 | 1 | xoo1 | xoo2 | xoo3
If i do:
SELECT idnode, max(version_no) FROM business
GROUP BY idnode ORDER BY idnode;
I get effectively only last version:
Idnode | version_no
111 | 2
222 | null
333 | 1
But as soon that i want to get texts, I don't know how to build the SQL.
In each SQL i tested i've been forced to put text column in a group by since
i used aggregate for version_no:
SELECT idnode, max(version_no), c1, c2, c3 FROM BUSINESS
GROUP BY idnode, c1, c2, c3 ORDER BY idnode;
But with that SQL, because of the group by and different values in text i
get
Idnode | version_no | c1 | c2 | c3
111 | 2 | foo1 | foo2 | foo3
111 | 1 | fee1 | foo2 | foo3
111 | null | fee1 | fee2 | fee3
222 | null | too1 | too2 | too3
333 | 1 | xoo1 | xoo2 | xoo3
333 | null | yoo1 | yoo2 | yee3
As we can't do aggregate in join neither in where, i can't get what i want.
Anybody could help me to build proper SQL ?
Thx for your answers.
Sébastien.
From | Date | Subject | |
---|---|---|---|
Next Message | Christian Kindler | 2007-10-24 09:55:06 | Re: get only rows for latest version of contents |
Previous Message | Harald Fuchs | 2007-10-24 09:19:26 | Re: request for help with COPY syntax |