'curson does not exist' asnswer from PostgreSQL - postgresql

Question

please your help...
object: a stored procedure whose ultimate purpose is writing flags in an specific column of a table. The flag location is decided based on the comparison of CURRENT values (i.e. in a 'current' row) and the values in the PRECEDING row.
General solution: using two cursors to scroll though the table.
It did work correctly using the standard structure, this is, cursors declared as :
cursor_evento_actual cursor for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc for update;
after that, I wanted the cursor declaration to accept different table names and colum names (taken from the procedure parameters), using EXECUTE. In order to do that I changed the way the cursor was declared: in the DECLARE section it went ...
cursor_evento_actual refcursor;
and in the BEGIN section it went...
open cursor_evento_actual for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc for update;
move cursor_evento_actual;
fetch cursor_evento_actual into vector_evento_actual;
Just the change described so far produced the error 'cursor does no exists'.
From what I see, it is not sintaxis... but I cannot find the problem
below, the procedure that works well and following, the procedure that doesn´t
the one that works, i.e., the one that correctly writes the flag 'repite' in the column 'aux_texto_1' of the selected table.
<<bloque_1>>
declare
vector_evento_actual record;
vector_evento_precedente record;
cursor_evento_actual cursor for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc for update;
cursor_evento_precedente cursor for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc;
begin
update public.camion_estado
set aux_texto_1 = DEFAULT;
open cursor_evento_actual;
open cursor_evento_precedente;
move cursor_evento_actual;
fetch cursor_evento_actual into vector_evento_actual;
fetch cursor_evento_precedente into vector_evento_precedente;
while (found) loop
if vector_evento_actual.calc_dt2 = vector_evento_precedente.calc_dt2 and vector_evento_actual.original_cam_id = vector_evento_precedente.original_cam_id then
update public.camion_estado
set aux_texto_1 = 'repite'
where current of cursor_evento_actual;
end if;
fetch cursor_evento_actual into vector_evento_actual;
fetch cursor_evento_precedente into vector_evento_precedente;
end loop;
close cursor_evento_actual;
close cursor_evento_precedente;
end bloque_1 $$;
...the key part of the code is.
update public.camion_estado set aux_texto_1 = 'repite'
where current of cursor_evento_actual;
after the changes in the way the cursos are declared, the coding looks like this:
(the RAISE NOTICE statements are there just for debugging)
declare
vector_evento_actual record;
vector_evento_precedente record;
cursor_evento_actual refcursor;
cursor_evento_precedente refcursor;
begin
update public.camion_estado
set aux_texto_1 = DEFAULT; -- asegurar que no está escrita de antes
open cursor_evento_actual for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc for update;
move cursor_evento_actual;
fetch cursor_evento_actual into vector_evento_actual;
open cursor_evento_precedente for
select * from public.camion_estado order by original_cam_id asc, calc_dt2 asc, original_num_post asc;
fetch cursor_evento_precedente into vector_evento_precedente;
raise notice 'inicio Bloque 1b - tabla actual: %, columna; % ', tabla_objeto, columna_objeto;
while (found) loop
if vector_evento_actual.calc_dt2 = vector_evento_precedente.calc_dt2 and vector_evento_actual.original_cam_id = vector_evento_precedente.original_cam_id then
raise notice 'este es repetido %', vector_evento_actual.original_cam_id;
execute 'update public.'||tabla_objeto||'
set aux_texto_1 = '||quote_literal('repite')||'
where current of cursor_evento_actual';
/*
update public.camion_estado
set aux_texto_1 = 'repite'
where current of cursor_evento_actual;
*/
end if;
fetch cursor_evento_actual into vector_evento_actual;
fetch cursor_evento_precedente into vector_evento_precedente;
end loop;
close cursor_evento_actual;
close cursor_evento_precedente;
This the code reporting 'Cursor does not exist'

Answer 1

If you use UPDATE ... WHERE CURRENT OF <cursor_name>, you are referring the actual name of the cursor (portal), not to the name of the PL/pgSQL variable. Since you didn't specify that name, it was automatically generated by PostgreSQL. Name the cursor the same as the variable with
cursor_evento_actual refcursor := 'cursor_evento_actual';