Handling multiple cursors with column of date datatype issue reg

Question

Dear all,
i am using three cursors in one pl/sql block each of this three cursor will fetch data based on column of date data type.i believe due to each condition relate to same table,contradiction may arise i.e
1> when code will execute , cursor c1 will do the job perfectly but c2 & c3 here may not be able to solve the purpose since the job has already been done by cursor c1 which i am not sure.my doubts i need all cursor to work based on each condition.
any suggestion from your side could sort out this issues.
Thanks n regards
Laxman
begin
for c1 in(select reqid from request where lastmoddate<sysdate - 8/24 and statuscode=1 and assigned_personid is not null)loop
update srequest set status=open where reqid=c1.reqid;
commit;
end loop;
for c2 in(select reqid from request where lastmoddate<sysdate - 1 and statuscode=1 and assigned_personid is null)loop
update srequest set status=open where reqid=c2.reqid;
commit;
end loop;
for c3 in(select reqid from request where lastmoddate<sysdate - 14 and statuscode=1 and assigned_personid is null)loop
update srequest set status=open where reqid=c3.reqid;
commit;
end loop;

Answer 1

If you look, your third cursor has already been included in your second cursor (sysdate - 14 < sysdate - 1), so there's only two conditions that you need to run.
You're also doing row-by-row aka slow-by-slow processing. It would be much, much better (*) if you converted this to one SQL statement - I've rewritten it to be a MERGE statement:
merge into srequest sreq
using (select reqid
       from   request
       where  statuscode = 1
       and    ((lastmoddate < sysdate - 8/24
                and assigned_person_id is not null)
               or
               (last_moddate < sysdate - 1
                and assigned_person_id is null))) req
  on (sreq.reqid = req.reqid)
when matched then
  update
    set status = 'OPEN';(*) more performant, easier to read, debug and maintain.