First_value

Question

Can anyone tell me if there is a more efficient way to do the following........
SELECT distinct accprf.account_id
first_value(accprf.value_start)
over (partition by accprf.account_id order by accprf.start_date) ,
first_value(accprf.value_end)
over (partition by accprf.account_id order by accprf.end_date desc)
FROM account_performance accprf
The table account_performance has more than one row per account_id. Each row has a start date and end date, with account performance information for that time interval. The above gets the values from the very first entry and the very last entry per account_id.
I was expecting to find a less complicated way to do the above.
Thanks, Mario.

Answer 1

Well, in that case it doesn't matter!
This is a little demonstration:
SQL> drop table t;
Table dropped.
SQL>
SQL> create table t (c1 number, c2 number, c3 number);
Table created.
SQL>
SQL> insert into t values (1, 1, 10);
1 row created.
SQL> insert into t values (1, 2, 11);
1 row created.
SQL> insert into t values (1, 3, 7);
1 row created.
SQL>
SQL>
SQL> insert into t values (2, 3, 20);
1 row created.
SQL> insert into t values (2, 4, 21);
1 row created.
SQL> insert into t values (2, 5, 15);
1 row created.
SQL>
SQL> SELECT c1,
  2          SUM(c3) keep (dense_rank first order by c2) sum,
  3          MIN(c3) keep (dense_rank first order by c2) min,
  4          MAX(c3) keep (dense_rank first order by c2) max
  5  FROM t
  6  group by c1;
        C1        SUM        MIN        MAX
         1         10         10         10
         2         20         20         20Message was edited by:
Michel
Sorry,
It have made an implicit assumption that c2 was unique or it is not true and then you are right. It must be min and not max to meet the first query.
Thanks for your correction.