Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax

On Monday 27 October 2003 21:35, Josh Berkus wrote:
> Alexander,
>
> > > BEGIN;
> > > DECLARE total CURSOR
> > > FOR SELECT=20
> > > SUBSTR(datetime,1,7)||'-01 00:00:00' as month,
> > > client,
> > > SUM(money)
> > > FROM stat
> > > WHERE SUBSTR(datetime,1,7)=3D'2003-10'
> > > GROUP BY month,client;
> > > DELETE FROM stat WHERE SUBSTR(datetime,1,7)=3D'2003-10';
> > > INSERT INTO stat FETCH ALL FROM total;
> > > COMMIT;

[ BTW: quoted-printable is evil ;) ]

> > >
> > > but it does not work, chokes on FETCH ALL.
>
> Well, there's two problems with your program:
>
> 1) INSERT INTO .... FETCH ALL is not currently implemented. You would need
> to use a loop, and insert one row at a time by value.

Exactly. I was saying that if implemented it may be useful.
My example is certainly doable without it but it quickly gets ugly
since I can't use this nifty trick.

> 2) You can't insert the rows you've just deleted from the base tables. In
> your example, the TOTAL cursor would be empty. I think that what you
> really want is a temp table.

Why do you think it would be empty? It is not. I tried this:

BEGIN;
DECLARE total CURSOR
FOR SELECT
SUBSTR(datetime,1,7)||'-01 00:00:00' as month,
client,
SUM(money)
FROM stat
WHERE SUBSTR(datetime,1,7)='2003-10'
GROUP BY month,client;
DELETE FROM stat WHERE SUBSTR(datetime,1,7)='2003-10';
FETCH ALL FROM total; <===================================
COMMIT;

and it does work as expected. FETCH spews out already deleted rows.
There is no problem with it.
--
Alexander Vlasenko