hi sean,
i tried the FOR-IN-EXECUTE methode before but i couldn't manage it. now i
got it. it's tricky and the code looks strange. the first trick is (you cant
use an integer as a result because in that case pgplsql would expext a
'normal' FOR i IN 2..5 LOOP.) i had to create a dummy type for the result.
CREATE TYPE attribute.temp AS (err INTEGER);
And then I misused an empty FOR LOOP as an assignment ...
###
CREATE OR REPLACE FUNCTION attribute.validate(TEXT,TEXT) RETURNS INTEGER AS
'
DECLARE
tmp RECORD;
cmd TEXT;
BEGIN
cmd := ''SELECT * FROM '' || $1 || ''('' || quote_literal($2) || '')'';
FOR tmp IN EXECUTE cmd LOOP END LOOP;
RETURN tmp.err;
END; '
LANGUAGE plpgsql;
###
but it works ...
thanks for the inspiration
sepp
its a problem that there is no example in the documentation for this
workaround :-<
From: Sean Davis <sdavis2@xxxxxxxxxxxx>
To: "Robert Wimmer" <seppwimmer@xxxxxxxxxxx>
CC: pgsql-interfaces@xxxxxxxxxxxxxx
Subject: Re: [INTERFACES] dynamic functions
Date: Thu, 5 May 2005 18:30:40 -0400
From the manual, you can use FOR-IN-EXECUTE or a cursor for pl/pgsql:
The results from SELECT commands are discarded by EXECUTE, and SELECT INTO
is not currently supported within EXECUTE. So there is no way to extract a
result from a dynamically-created SELECT using the plain EXECUTE command.
There are two other ways to do it, however: one is to use the
FOR-IN-EXECUTE loop form described in Section 35.7.4, and the other is to
use a cursor with OPEN-FOR-EXECUTE, as described in Section 35.8.2.
Does this help any? If not, they you could use another procedure language
like pl/perl or others. With many of them, you can build the SQL query,
then execute it and get the returned results. Again, see the manual
section for pl/perl (for example,
http://www.postgresql.org/docs/8.0/static/plperl-database.html) and others.
Sean
On May 5, 2005, at 5:49 PM, Robert Wimmer wrote:
hi ,
is there any way to build "dynamic functions" in plpgsql ?
my problem is, i have a table defining attributes like
CREATE TABLE attribute.attribute (
name NAME PRIMARY KEY,
descr VARCHAR(256),
regex VARCHAR(50) NOT NULL,
minlen INTEGER NOT NULL DEFAULT 0,
maxlen INTEGER NOT NULL DEFAULT 64
-- validate NAME // not implemented
);
and a function like
CREATE OR REPLACE FUNCTION
attribute.match(TEXT,TEXT,BOOLEAN) RETURNS INTEGER AS '
.. check the value (against the regex etc) ..
END; ' LANGUAGE plpgsql
in some cases i would like to check the values also against a function for
example
CREATE FUNCTION attribute.check_range(TEXT) RETURNS INTEGER AS '
BEGIN
IF $1 ... THEN RETURN -1; END IF;
RETURN 0;
END; '
....
so that i can do the following in my match function
CREATE OR REPLACE FUNCTION
attribute.match(TEXT,TEXT,BOOLEAN) RETURNS INTEGER AS '
.. check the value (against the regex etc) ..
IF attrib.validate NOT IS NULL THEN
cmd := atrib.validate || ''('' $1 '')'' ||;
-- ??
-- EXECUTE ''SELECT '' || cmd; // SELECT does not work in EXECUTE
-- ??
END IF
END; ' LANGUAGE plpgsql
is there a way to get a result back from EXECUTE ?
i hope you can understand my description of the problem
i am using postgresQL 7.4 on debian
thanx
sepp
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