POSTGRESQL - FUNCTION SELECT + UPDATE - postgresql

Question

I need execute update for each return of the select, but I don't know how I can do it.
In firebird I have this code:
BEGIN
FOR
SELECT data_cadastro || ' ' || hora_cadastro as data_hora_cadastro,codigo_alteracao_convenio
FROM CC_ALTERACAO_CONVENIO
INTO:data_hora_cadastro,codigo_alteracao_convenio
DO
BEGIN
update CC_ALTERACAO_CONVENIO
set data_hora_cadastro = :data_hora_cadastro
where codigo_alteracao_convenio = :codigo_alteracao_convenio;
suspend;
END
END
I want change to function in postgresql.
I tried this, but not work because I don't know the syntax of postgresql of how can I do it.
CREATE OR REPLACE FUNCTION sim.ajuste_alteracao_convenio(OUT data_hora_cadastro character varying, OUT codigo_alteracao_convenio integer)
RETURNS SETOF record AS
$BODY$
DECLARE
v_data_hora_cadastro character varying;
v_codigo_alteracao_convenio INTEGER;
BEGIN
RETURN QUERY
SELECT data_cadastro || ' ' || hora_cadastro as data_hora_cadastro,codigo_alteracao_convenio
FROM sim.CC_ALTERACAO_CONVENIO
--loop
BEGIN
update sim.CC_ALTERACAO_CONVENIO
set data_hora_cadastro = v_data_hora_cadastro
where codigo_alteracao_convenio = v_codigo_alteracao_convenio;
END
--END LOOP;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;
Could someone give me a direction of how can I solved this?
SOLVED
create type foo as (
data_hora_cadastro timestamp,
codigo_alteracao_convenio integer
)
CREATE OR REPLACE FUNCTION sim.ajuste_alteracao_convenio3()
RETURNS SETOF foo AS
$BODY$
DECLARE
r foo%rowtype;
BEGIN
FOR r IN SELECT data_cadastro || ' ' || hora_cadastro as data_hora_cadastro,codigo_alteracao_convenio FROM sim.CC_ALTERACAO_CONVENIO
LOOP
update sim.CC_ALTERACAO_CONVENIO
set data_hora_cadastro = r.data_hora_cadastro
where codigo_alteracao_convenio = r.codigo_alteracao_convenio;
RETURN NEXT r; -- return current row of SELECT
END LOOP;
RETURN;
END
$BODY$
LANGUAGE 'plpgsql' ;
Thank you all

Answer 1

Information is missing in the question, but it looks like all you need is a simple UPDATE with RETURNING:
UPDATE sim.cc_alteracao_convenio a
SET data_hora_cadastro = a.data_cadastro + a.hora_cadastro
RETURNING a.data_hora_cadastro, a.codigo_alteracao_convenio;
Assuming data_cadastro is data type date and hora_cadastro is data type time. Currently, you convert both to text, concatenate and cast back to timestamp. That's much more expensive than it needs to be. Just add both together: data_cadastro + hora_cadastro
The UPDATE itself looks like you are storing functionally dependent values redundantly. Once you've updated data_hora_cadastro you can drop data_cadastro and hora_cadastrocan.
If you positively need a function:
CREATE OR REPLACE FUNCTION sim.ajuste_alteracao_convenio3()
RETURNS TABLE (data_hora_cadastro timestamp
, codigo_alteracao_convenio integer) AS
$func$
UPDATE sim.cc_alteracao_convenio a
SET data_hora_cadastro = a.data_cadastro + a.hora_cadastro
RETURNING a.data_hora_cadastro, a.codigo_alteracao_convenio;
$func$ LANGUAGE sql; -- never quote the language name
You don't need to create a composite type, just use RETURNS TABLE() instead.
Or, if you need pre-UPDATE values:
Return pre-UPDATE Column Values Using SQL Only - PostgreSQL Version

Answer 2

this is what I do, it's an idea but may be it inspires you:
WITH insusu AS (
SELECT data_cadastro || ' ' || hora_cadastro
as data_hora_cadastro,codigo_alteracao_convenio
FROM sim.CC_ALTERACAO_CONVENIO
RETURNING id
)
update sim.CC_ALTERACAO_CONVENIO
set data_hora_cadastro =:data_hora_cadastro
from insusu;
select *
from insusu;
The Objetive is uses a with to determine with what data need work.