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* extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax
@ 2003-10-23 21:00 Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
2003-10-27 16:39 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Christoph Haller <ch@rodos.fzk.de>
0 siblings, 1 reply; 4+ messages in thread
From: Alexander Vlasenko @ 2003-10-23 21:00 UTC (permalink / raw)
To: pgsql-general@postgresql.org
Please CC me, I am not subscribed.
An imaginary SQL statement
INSERT INTO table FETCH ... FROM cursor;
looks almost the same as currently available
INSERT INTO table SELECT ...;
I tried it because I needed to insert a row in a table
after I DELETEd a set of rows, something like 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';
INSERT INTO stat FETCH ALL FROM total;
COMMIT;
but it does not work, chokes on FETCH ALL.
I want to sum up all the money by month, delete all the rows
(possibly thousands of them) and insert one row per client
with monthly totals.
Obviously I cannot swap order of INSERT and DELETE here.
I hesitate to post this to pgsql-hackers@postgresql.org,
do I have to? ;)
--
Alexander Vlasenko
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax
2003-10-23 21:00 extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
@ 2003-10-27 16:39 ` Christoph Haller <ch@rodos.fzk.de>
2003-10-27 19:35 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Josh Berkus <josh@agliodbs.com>
0 siblings, 1 reply; 4+ messages in thread
From: Christoph Haller @ 2003-10-27 16:39 UTC (permalink / raw)
To: intrnl_edu@ilyichevsk.odessa.ua; +Cc: pgsql-sql
>
> Please CC me, I am not subscribed.
>
> An imaginary SQL statement
> INSERT INTO table FETCH ... FROM cursor;
> looks almost the same as currently available
> INSERT INTO table SELECT ...;
>
> I tried it because I needed to insert a row in a table
> after I DELETEd a set of rows, something like this:
>
> 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;
>
> but it does not work, chokes on FETCH ALL.
>
> I want to sum up all the money by month, delete all the rows
> (possibly thousands of them) and insert one row per client
> with monthly totals.
>
> Obviously I cannot swap order of INSERT and DELETE here.
>
> I hesitate to post this to pgsql-hackers@postgresql.org,
> do I have to? ;)
>
> --=20
> Alexander Vlasenko
>
Using a temporary table to buffer the result comes to mind.
Regards, Christoph
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax
2003-10-23 21:00 extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
2003-10-27 16:39 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Christoph Haller <ch@rodos.fzk.de>
@ 2003-10-27 19:35 ` Josh Berkus <josh@agliodbs.com>
2003-10-27 19:54 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
0 siblings, 1 reply; 4+ messages in thread
From: Josh Berkus @ 2003-10-27 19:35 UTC (permalink / raw)
To: Christoph Haller <ch@rodos.fzk.de>; intrnl_edu@ilyichevsk.odessa.ua; +Cc: pgsql-sql
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;
> >
> > 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.
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.
--
-Josh Berkus
Aglio Database Solutions
San Francisco
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax
2003-10-23 21:00 extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
2003-10-27 16:39 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Christoph Haller <ch@rodos.fzk.de>
2003-10-27 19:35 ` Re: extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Josh Berkus <josh@agliodbs.com>
@ 2003-10-27 19:54 ` Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
0 siblings, 0 replies; 4+ messages in thread
From: Alexander Vlasenko @ 2003-10-27 19:54 UTC (permalink / raw)
To: josh@agliodbs.com, Christoph Haller <ch@rodos.fzk.de>; +Cc: pgsql-sql
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
^ permalink raw reply [nested|flat] 4+ messages in thread
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2003-10-23 21:00 extend INSERT by 'INSERT INTO table FETCH ... FROM cursor' syntax Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
2003-10-27 16:39 ` Christoph Haller <ch@rodos.fzk.de>
2003-10-27 19:35 ` Josh Berkus <josh@agliodbs.com>
2003-10-27 19:54 ` Alexander Vlasenko <intrnl_edu@ilyichevsk.odessa.ua>
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