по памяти:

create type otype as object (id_appointment number);
create type ottype as table of otype;
declare
n ottype:=ottype();
begin
...
<заполнили n>
select * from table(cast(n as ottype)) where id_appointment number = 1
...
end;

Расширенный пример на страничке у Vladimir Begun http://vbegun.net/