(I)

#1

select aname from agents
 where percent > (select max(percent) from agents where city='Dallas')
  and aid not in (select distinct aid from customers c, orders o
    where city='Dallas' and c.cid=o.cid);


#2

select cid from customers c
  where not exists (select pid from orders o1
    where aid='a05' and not exists (select * from orders o2
      where o2.cid=c.cid and o2.pid=o1.pid ));


#3

select aid, aname from agents a
  where not exists (select pid from orders o1
    where cid='c002' and not exists (select * from agents a2, orders o2
      where o2.aid=a.aid and o1.pid=o2.pid and a.percent > a2.percent));



(III)

#1

exec sql begin declare section;
  char cust_id[5], agent_id[4], prod_id[4];
  int ord_no, ord_qty, start_ordno, prod_qty;
exec sql end declare  section;


#2

exec sql declare ordc cursor for 
  select ordno, cid, aid, o.pid, qty, quantity from orders o, products p
    where ordno >= :start_ordno and o.pid = p.pid
      order by pid for update of quantity;


#3

exec sql whenever not found goto clcurs;
exec sql open ordc;
while( sqlca.sqlcode==0 ){
  exec sql fetch ordc 
    into :ord_no, :cust_id, :agent_id, :prod_id, :ord_qty, prod_qty;
  if( ord_qty <= prod_qty )
    exec sql update products 
      set quantity=(:prod_qty-:ord_qty)
        where current of ordc;
  esle
    exec sql insert into back_orders
      values(ord_no, cust_id, agent_id, prod_id, ord_qty);
}
clsurs:
exec sql close ordc;
exec sql whenever not found continue;