use a validation function for an element in apex 5.0 - sql

Question

I am trying to implement a validation on an application item in APEX 5.0. I am using a PL/SQL function returning a boolean
begin
if exists (select id_referencia
from items
where id_referencia = :P2_REFERENCIA)
then
return true;
else
return false;
end if;
end;
When I submit my page, I get the following error
ORA-06550: line 2, column 4: PLS-00204: function or pseudo-column
'EXISTS' may be used inside a SQL statement only ORA-06550: line 2,
column 1: PL/SQL: Statement ignored

Answer 1

if exists isn't valid PL/SQL syntax.
You could do a count(*) instead
declare
l_cnt integer;
begin
select count(*)
into l_cnt
from items
where id_referencia = :P2_REFERENCIA;
if( l_cnt >= 1 )
then
return true;
else
return false;
end if;
end;
If you really wanted to do an exists, you'd do something like this. I don't know why you'd want to do this assuming that id_referencia is the primary key of the table. But you could
declare
l_exists integer;
begin
begin
select 1
into l_exists
from dual
where exists( select 1
from items
where id_referencia = :P2_REFERENCIA );
exception
when no_data_found
then
l_exists := 0;
end;
if( l_exists = 1 )
then
return true;
else
return false;
end if;
end;

Answer 2

If you want to use EXISTS in a PL/SQL function returning BOOLEAN,try this
DECLARE
v_exist NUMBER;
BEGIN
SELECT 1
INTO v_exist
FROM DUAL WHERE EXISTS (select id_referencia
from items
where id_referencia = :P2_REFERENCIA)
IF v_exist IS NOT NULL
THEN
RETURN true;
ELSE
RETURN false;
END IF;
END;