Variable date depending on time - oracle

Question

I got a question. I have a query that will be running as part of a night job. This query is supposed to give me all actions that have taken place during that day. However, and this is the tricky part, it won't always be run on the same time.
Because it is part of a night job, it could happen that on day 1, the query runs at 00:05, and on day 2, it runs on 23:55. This is complicating the query, because I can't say use today's date or use yesterday's date.
I got the following query so far:
select deuda_id from deuda where n_expediente in
(select
(case when to_char(sysdate, 'HH24:MI:SS') between '00:00:00' and '12:00:00' then
(select n_expediente from cartas_enviadas where codigo_carta in ('OIEUR','OIGBP') and f_envio > trunc(sysdate-1)
) else
(select n_expediente from cartas_enviar where codigo_carta in ('OIEUR','OIGBP')
)
) from dual
);
A little explanation: (the database is in Spanish/Italian):
deuda_id is the unique invoice number.
n_expediente is the case number (for this client always unique).
f_envio is the execution date.
codigo_carta is the action type.
Cartas_enviar holds all the actions that are due. When the action is taken, f_envio is entered. Overnight, all actions that have been executed, will be moved from cartas_enviar to cartas_enviadas).
Wat I am trying to do is the following:
I want to look at the current time. If it is before midnight, I want to look at the table cartas_enviar, and take the n_expediente from there, but only if the action is OIEUR or OIGBP. If it is after midnight, I want to look at the table cartas_enviadas, and take the n_expediente from there, but only if the action is OIEUR or OIGBP, and if the action has been executed yesterday.
However, when I am trying to execute this query, I am getting the following error message:
ORA-00905: missing keyword.
Could someone please help me with this query?
PS: It is an Oracle database

Answer 1

The problem is that you can't pull many values like that from subquery of a subquery to pass them back. Try this approach instead:
select deuda_id
from deuda
where
(to_char(sysdate, 'HH24:MI:SS') between '00:00:00' and '12:00:00'
AND n_expediente IN (select n_expediente
from cartas_enviadas
where codigo_carta in ('OIEUR','OIGBP')
and f_envio > trunc(sysdate-1) ))
OR (NOT to_char(sysdate, 'HH24:MI:SS') between '00:00:00' and '12:00:00'
AND n_expediente IN (select n_expediente
from cartas_enviar
where codigo_carta in ('OIEUR','OIGBP')))
;