Opti im

Question

Hi everyone,
My table CALLS has the following contents:
Cust id CountryCalled Duration
123 SG 10
123 SG 20
123 THA 50
123 IND 80
456 US 30
I need to find the CountryCalled with the maximum sunmed duration:
Cust id CountryCalled
123 IND
456 US
Does someone have an efficient query to achieve this? I am using Oracle8i. Thanks!

Answer 1

or if you do not want to us a GROUP BY clause:
SQL> select * from calls;
   CUST_ID COU   DURATION
       123 SG          70
       123 SG          30
       123 THA         50
       123 IND         80
       456 US          30
SQL> select c2.cust_id, c2.countrycalled
  2    from (select c1.cust_id, c1.countrycalled, c1.duration,
  3                 count(*) over (partition by c1.cust_id order by c1.cust_id) ct,
  4                 row_number() over (partition by c1.cust_id order by c1.cust_id, c1.duration) rt
  5            from (select distinct cust_id, countrycalled,
  6                         sum(duration) over (partition by cust_id,
  7                                               countrycalled order by cust_id) duration
  8                    from calls) c1) c2
  9   where c2.ct = c2.rt
10  order by c2.rt;
   CUST_ID COU
       456 US
       123 SG
SQL>