How to get last row and sum of all columns in one query

Question

Hi ,
is there a way to get last record for a column and sum of all record for another column in the same query.
Best Regards ,

Answer 1

You should define your requirements properly for volunteers to help here..
Your data is not good enough to provide you accurate solution. Reason being you dont have a proper column which differentiates between first and last entry.
The solution becomes easy based on your desgin.
I have introduced a grouping column called "id" and a time column called "time_of_insert" (only this way you can confidently say that you can differentiate between first and last (also a fool proof solution) --- you may optionally use sequence(instead of date though if you say you may end up inserting two rows at the same time, then probably sequence would be a better choice to differentiate rather than a timestamp field) etc...)
With your sample data something like this can be done to achieve your desired result.
WITH dataset AS
        (SELECT 1 id,10 used, 8 remain,systimestamp+1/24 time_of_insert FROM DUAL
         UNION ALL
         SELECT 1 id, 1, 7,systimestamp+2/24 FROM DUAL
         UNION ALL
         SELECT 1 id,2, 5,systimestamp+3/24 FROM DUAL
         UNION ALL
         SELECT 1 id,1, 0,systimestamp+4/24 FROM DUAL
         UNION ALL
         SELECT 1 id,0, 0,systimestamp+5/24 FROM DUAL
         UNION ALL
         SELECT 1 id,1, 4,systimestamp+6/24 FROM DUAL)
SELECT *
  FROM (SELECT SUM (used) OVER () sum_all,
               FIRST_VALUE (remain)
                  OVER (PARTITION BY id ORDER BY time_of_insert DESC)
                  last_row
          FROM dataset)
WHERE ROWNUM = 1;
Output:
SUM_ALL       LAST_ROW
15                  4
Cheers,
Manik.