trigger to set date automatic after update - triggers

Question

Some background info: i have a table named defects which has column named status_id and another column named date_closed ,i want to set date_closed after status_id has been updated
i already try to do this using after update trigger with the following code:
after update on eba_bt_sw_defects
for each row
declare
l_status number(20) := null;
begin
select status_id into l_status from eba_bt_sw_defects D,eba_bt_status S where D.status_id = S.id;
if l_status in ( select id from eba_bt_status where is_open = 'N' and NVL(is_enhancement,'N')='N') then
:NEW.DATE_CLOSED := LOCALTIMESTAMP ;
end if;
end;
but an error occured ( subquery not allowed in this contextCompilation failed)
i want a help

Answer 1

A couple of things that need fixing in your code:
In a trigger do not select from the table the trigger you're on. This will probably raise a ORA-04091: table name is mutating, trigger/function may not see it error.
IF l_variable IN (SELECT ...) is not a valid oracle syntax. It raises PLS-00405: subquery not allowed in this context
I don't have your data so here is a similar example:
drop table todos;
drop table statuses;
-- create tables
create table statuses (
id number generated by default on null as identity
constraint statuses_id_pk primary key,
status varchar2(60 char),
is_open varchar2(1 char) constraint statuses_is_open_ck
check (is_open in ('Y','N'))
)
;
create table todos (
id number generated by default on null as identity
constraint todos_id_pk primary key,
name varchar2(255 char) not null,
close_date timestamp with local time zone,
status_id number
constraint todos_status_id_fk
references statuses on delete cascade
)
;
-- load data
insert into statuses (id, status, is_open ) values (1, 'OPEN', 'Y' );
insert into statuses (id, status, is_open ) values (2, 'COMPLETE', 'N' );
insert into statuses (id, status, is_open ) values (3, 'ON HOLD', 'Y' );
insert into statuses (id, status, is_open ) values (4, 'CANCELLED', 'N' );
commit;
insert into todos (name, close_date, status_id ) values ( 'Y2 Security Review', NULL, 1 );
-- triggers
CREATE OR REPLACE TRIGGER todos_biu BEFORE
INSERT OR UPDATE ON todos
FOR EACH ROW
DECLARE
l_dummy NUMBER;
BEGIN
SELECT
1
INTO l_dummy
FROM
statuses
WHERE
is_open = 'N' AND
id = :new.status_id;
:new.close_date := localtimestamp;
EXCEPTION
WHEN no_data_found THEN
-- I'm assuming you want close_date to NULL if todo is re-opened.
:new.close_date := NULL;
END todos_biu;
/
update todos set status_id = 2;
select * from todos;
id name close_date status_id
1 Y2 Security Review 11-MAY-22 05.27.04.987117000 PM 2