I did already, but this still does not help me write a simple while loop
that goes through all data and stops at the last row.
Joris Dobbelsteen wrote:
See the postgresql documentation at:
http://www.postgresql.org/docs/8.2/interactive/plpgsql-cursors.html
-----Original Message-----
From: pgadmin-support-owner@xxxxxxxxxxxxxx
[mailto:pgadmin-support-owner@xxxxxxxxxxxxxx] On Behalf Of
Anton Andreev
Sent: dinsdag 24 april 2007 13:45
To: pgadmin-support@xxxxxxxxxxxxxx
Subject: [pgadmin-support] questions about cursors
Hi,
I am trying to use cursors and I am really frustrated already.
Do I need to install an extension?
1. Problem number one is that what ever I use in front of the
fetch command it is not being accepted, it gives a syntax
error. If I use a number ,"all" or "forward" it gives an error
again?????????? I want to do something like the code below:
CREATE OR REPLACE FUNCTION database_correction()
RETURNS double precision AS
$BODY$
DECLARE
mycursor CURSOR FOR select distinct(fund_id) from
"NAV_values_bfb_history";
iterator integer;
BEGIN
open mycursor;
Please see chapter 37.8.3.1 "FETCH" (in the 8.2 documentation).
Important for you is: "As with SELECT INTO, the special variable FOUND
may be checked to see whether a row was obtained or not."
FETCH mycursor INTO iterator;
--fetch next from mycursor --gives an error
WHILE (FOUND) LOOP
-- compute
FETCH mycursor INTO interator;
END LOOP;
-- instead of
WHILE (FETCH next from mycursor) LOOP
-- some computations here
END LOOP;
I believe this should work. I've never really used cursors before, as I
can usually do it with regular SQL statements (which are usually
faster).
I should also advise that you can create your own aggregate (see CREATE
AGGREGATE in the documentation), which might, or might not, be easier
for your purposes.
CLOSE mycursor;
END;
2. What is the right way to check that the cursor has ended.
In sqlserver there is a variable "@@fetch_status". I have to
make here some comparison in the while clause, but I am not
sure what it should be. I could not find a single example for
cursor in a loop.
When FOUND evaluates to false, you should have completed. (In case of
errors, you will probably have an exception being thrown).
I will greatly appreciate any help, pgsql is my database of choice.
Hope this helps...
- Joris
