Recursive with cursor on psql, nothing data found - postgresql

Question

How to use a recursive query and then using cursor to update multiple rows in postgresql. I try to return data but no data is found. Any alternative to using recursive query and cursor, or maybe better code please help me.
drop function proses_stock_invoice(varchar, varchar, character varying);
create or replace function proses_stock_invoice
(p_medical_cd varchar,p_post_cd varchar, p_pstruserid character varying)
returns void
language plpgsql
as $function$
declare
cursor_data refcursor;
cursor_proses refcursor;
v_medicalCd varchar(20);
v_itemCd varchar(20);
v_quantity numeric(10);
begin
open cursor_data for
with recursive hasil(idnya, level, pasien_cd, id_root) as (
select medical_cd, 1, pasien_cd, medical_root_cd
from trx_medical
where medical_cd = p_pstruserid
union all
select A.medical_cd, level + 1, A.pasien_cd, A.medical_root_cd
from trx_medical A, hasil B
where A.medical_root_cd = B.idnya
)
select idnya from hasil where level >=1;
fetch next from cursor_data into v_medicalCd;
return v_medicalCd;
while (found)
loop
open cursor_proses for
select B.item_cd, B.quantity from trx_medical_resep A
join trx_resep_data B on A.medical_resep_seqno = B.medical_resep_seqno
where A.medical_cd = v_medicalCd and B.resep_tp = 'RESEP_TP_1';
fetch next from cursor_proses into v_itemCd, v_quantity;
while (found)
loop
update inv_pos_item
set quantity = quantity - v_quantity, modi_id = p_pstruserid, modi_id = now()
where item_cd = v_itemCd and pos_cd = p_post_cd;
end loop;
close cursor_proses;
end loop;
close cursor_data;
end
$function$;
but nothing data found?

Answer 1

You have a function with return void so it will never return any data to you. Still you have the statement return v_medicalCd after fetching the first record from the first cursor, so the function will return from that point and never reach the lines below.
When analyzing your function you have (1) a cursor that yields a number of idnya values from table trx_medical, which is input for (2) a cursor that yields a number of v_itemCd, v_quantity from tables trx_medical_resep, trx_resep_data for each idnya, which is then used to (3) update some rows in table inv_pos_item. You do not need cursors to do that and it is, in fact, extremely inefficient. Instead, turn the whole thing into a single update statement.
I am assuming here that you want to update an inventory of medicines by subtracting the medicines prescribed to patients from the stock in the inventory. This means that you will have to sum up prescribed amounts by type of medicine. That should look like this (note the comments):
CREATE FUNCTION proses_stock_invoice
-- VVV parameter not used
(p_medical_cd varchar, p_post_cd varchar, p_pstruserid varchar)
RETURNS void AS $function$
UPDATE inv_pos_item -- VVV column repeated VVV
SET quantity = quantity - prescribed.quantity, modi_id = p_pstruserid, modi_id = now()
FROM (
WITH RECURSIVE hasil(idnya, level, pasien_cd, id_root) AS (
SELECT medical_cd, 1, pasien_cd, medical_root_cd
FROM trx_medical
WHERE medical_cd = p_pstruserid
UNION ALL
SELECT A.medical_cd, level + 1, A.pasien_cd, A.medical_root_cd
FROM trx_medical A, hasil B
WHERE A.medical_root_cd = B.idnya
)
SELECT B.item_cd, sum(B.quantity) AS quantity
FROM trx_medical_resep A
JOIN trx_resep_data B USING (medical_resep_seqno)
JOIN hasil ON A.medical_cd = hasil.idnya
WHERE B.resep_tp = 'RESEP_TP_1'
--AND hacil.level >= 1 Useless because level is always >= 1
GROUP BY 1
) prescribed
WHERE item_cd = prescribed.item_cd
AND pos_cd = p_post_cd;
$function$ LANGUAGE sql STRICT;
Important
As with all UPDATE statements, test this code before you run the function. You can do that by running the prescribed sub-query separately as a stand-alone query to ensure that it does the right thing.