oracle rollup function with multiple columns

Question

I've a simple query:

WITH data(val1, val2, val3) AS
     ( SELECT 'a' ,'a-details' ,'1' FROM DUAL
     UNION ALL
     SELECT 'b' ,'b-details' ,'2' FROM DUAL
     UNION ALL
     SELECT 'c' ,'c-details' ,'3' FROM DUAL
     )
SELECT NVL(val1,'Total Result'),
     val2,
     SUM(val3) tot
from data
group by rollup(val1, val2);

I get an output like:

VAL1                             VAL2                                    TOT
-------------------------------- -------------------------------- ----------
a                                a-details                                 1 
a                                                                          1 
b                                b-details                                 2 
b                                                                          2 
c                                c-details                                 3 
c                                                                          3 
Total Result                                                               6 

But I need an output like:

VAL1                             VAL2                                    TOT
-------------------------------- -------------------------------- ----------
a                                a-details                                 1 
b                                b-details                                 2 
c                                c-details                                 3 
Total Result                                                               6 

Thanks in advance.

Answer 1

I find it rather easier to specify the exact sets I need with the GROUPING SET clause:

WITH data(val1, val2, val3) AS
     ( SELECT 'a' ,'a-details' ,'1' FROM DUAL
     UNION ALL
     SELECT 'b' ,'b-details' ,'2' FROM DUAL
     UNION ALL
     SELECT 'c' ,'c-details' ,'3' FROM DUAL
     )
SELECT NVL(val1,'Total Result'),
     val2,
     SUM(val3) tot
from data
group by grouping sets ((val1, val2),());

I suspect that it is more efficient, as it directly specifies the levels to calculate.

http://sqlfiddle.com/#!4/8301d/3

CUBE and ROLLUP are handy for generating large numbers of aggregation levels automatically (eg. every level in a dimensional hierarchy), and there might be a case for using GROUPING ID if you wanted to eliminate a small subset of levels from a large CUBE-generated set, but GROUPING SET is precisely designed for specifying particular aggregation levels.