Re: plpgsql dynamic queries and optional arguments

Curtis,

Here is an example function that uses dynamic sql.
I use it under 7.4.5

Hope this helps.

Allan

-- Function to delete old data out of the point tables.
-- tablename is a column in the points table that holds the name
-- of the table in which this points data is stored.

create or replace function delete_old() returns integer as '
declare
pt record;
count integer;
sql_str varchar(512);

begin
count := 0;
for pt in select * from points loop
sql_str := ''deleting from '' || pt.tablename || '' data older than '' || pt.savefor::varchar || '' days'';
-- raise notice ''%'', sql_str;
sql_str := ''delete from '' || pt.tablename || '' where dt < (now() - interval '''''' || pt.savefor::varchar || '' days'''')::timestamp;'';
execute sql_str;
count := count + 1;
end loop;

return count;
end;
' LANGUAGE plpgsql;

-----Original Message-----
From: pgsql-general-owner(at)postgresql(dot)org [mailto:pgsql-general-owner(at)postgresql(dot)org]On Behalf Of Curtis Scheer
Sent: Wednesday, 16 August 2006 3:22 AM
To: pgsql-general(at)postgresql(dot)org
Subject: [GENERAL] plpgsql dynamic queries and optional arguments

I have a table that I would like to be able to retrieve information out of based on a combination of multiple columns and I would like to be able to do this through a plpgsql stored procedure. Right now I have multiple stored procedures that I am calling based on the values parameter values I pass them and I am using static sql. The problem with this is it doesn't scale as well as I would like it to because when I add another column of information to the table that needs to be used for retrieval it adds another level of combinations.

Also, when dealing with null values with static sql I use the same exact sql statement except for the where clause containing the "column1 is null" versus "column1 = passedvalue". Anyways, I have made a simple example procedure and table; any help would be greatly appreciated basically I would like to use dynamic sql instead of static but I have unsuccessfully been able to retrieve the results of a dynamic sql statement in a pgplsql procedure. Here is the example table and stored procedure.

CREATE TABLE public.foo
(
fooid int4 NOT NULL DEFAULT nextval('foo_fooid_seq'::regclass),
foo_date timestamp NOT NULL,
footypeid int4 NOT NULL,
footext varchar,
CONSTRAINT pk_fooid PRIMARY KEY (fooid)
)
WITHOUT OIDS;
ALTER TABLE public.foo OWNER TO fro;


CREATE OR REPLACE FUNCTION public.get_nextfoo(pfoo_date "timestamp", pfoovalue int4, pfootext bpchar)
RETURNS SETOF public.foo AS
$BODY$DECLARE
rec foo%ROWTYPE;
BEGIN
if pfootext is null then
SELECT
*
INTO
rec
FROM
foo
WHERE
foo_date = pfoo_date
and foovalue = pfoovalue
and footext is null
For Update;
else
SELECT
*
INTO
rec
FROM
foo
WHERE
foo_date = pfoo_date
and foovalue = pfoovalue
and footext = pfootext
For Update;
end if;
RETURN NEXT rec;
return;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION public.get_nextfoo(pfoo_date "timestamp", pfoovalue int4, pfootext bpchar) OWNER TO fro;

insert into foo(foo_date,foovalue,footext) values('2006-08-15',1,'bar');
insert into foo(foo_date,foovalue,footext) values('2006-08-14',1,'bar');
insert into foo(foo_date,foovalue,footext) values('2006-08-15',2,'bar');
insert into foo(foo_date,foovalue,footext) values('2006-08-14',2,'bar');
insert into foo(foo_date,foovalue) values('2006-08-15',1);
insert into foo(foo_date,foovalue) values('2006-08-14',1);
insert into foo(foo_date,foovalue) values('2006-08-15',2);
insert into foo(foo_date,foovalue) values('2006-08-14',2);



Thanks,
Curtis

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