Re: get only rows for latest version of contents

Hi!

not quick mut works

select * from business b1
where b1.version_no = (SELECT max(version_no) FROM business b2.
where b2.idnode = b1.idnode
)

If you want to make this quiry faster du a regular join

select b1.*
from business b1,
(SELECT max(version_no) FROM business b2.
where b2.idnode = b1.idnode
) as b2
where b1.idnode = b2.idnode
and b1.version_no = b2.version_nr

Regards Chris

PS written without running any sql, maybe there are some syntax issues, but i am shure you will figure these out :-)

On Wed, October 24, 2007 11:29 am, Sébastien Meudec wrote:
> 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.
>
>
>
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--
cu
Chris

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