Display the 3rd hieghest value without using rowid

Question

HI All,
Can any one help me how to display the 3rd hieghest valuer without using a ROWID..
Thanks
Basava

Answer 1

Frank, using ROWNUM = 1 instead of DISTINCT could be a bit faster:
SQL> SET LINESIZE 132
SQL> EXPLAIN PLAN FOR
  2  WITH got_r_num AS (
  3                     SELECT  DISTINCT sal,
  4                                      DENSE_RANK() OVER(ORDER BY sal DESC NULLS LAST) AS r_num
  5                       FROM  scott.emp
  6                    )
  7  SELECT  sal
  8    FROM  got_r_num
  9    WHERE r_num = 3
10  /
Explained.
SQL> @?\RDBMS\ADMIN\UTLXPLS
PLAN_TABLE_OUTPUT
Plan hash value: 436395657
| Id  | Operation                 | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT          |      |     9 |   234 |     5  (40)| 00:00:01 |
|*  1 |  VIEW                     |      |     9 |   234 |     5  (40)| 00:00:01 |
|   2 |   HASH UNIQUE             |      |     9 |    36 |     5  (40)| 00:00:01 |
|*  3 |    WINDOW SORT PUSHED RANK|      |     9 |    36 |     5  (40)| 00:00:01 |
|   4 |     TABLE ACCESS FULL     | EMP  |    14 |    56 |     3   (0)| 00:00:01 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   1 - filter("R_NUM"=3)
   3 - filter(DENSE_RANK() OVER ( ORDER BY INTERNAL_FUNCTION("SAL") DESC
              NULLS LAST)<=3)
18 rows selected.
SQL> EXPLAIN PLAN FOR
  2  WITH got_r_num AS (
  3                     SELECT  sal,
  4                             DENSE_RANK() OVER(ORDER BY sal DESC NULLS LAST) AS r_num
  5                       FROM  scott.emp
  6                    )
  7  SELECT  sal
  8    FROM  got_r_num
  9    WHERE r_num = 3
10      AND ROWNUM = 1
11  /
Explained.
SQL> @?\RDBMS\ADMIN\UTLXPLS
PLAN_TABLE_OUTPUT
Plan hash value: 21859616
| Id  | Operation                 | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT          |      |     1 |    26 |     4  (25)| 00:00:01 |
|*  1 |  COUNT STOPKEY            |      |       |       |            |          |
|*  2 |   VIEW                    |      |    14 |   364 |     4  (25)| 00:00:01 |
|*  3 |    WINDOW SORT PUSHED RANK|      |    14 |    56 |     4  (25)| 00:00:01 |
|   4 |     TABLE ACCESS FULL     | EMP  |    14 |    56 |     3   (0)| 00:00:01 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   1 - filter(ROWNUM=1)
   2 - filter("R_NUM"=3)
   3 - filter(DENSE_RANK() OVER ( ORDER BY INTERNAL_FUNCTION("SAL") DESC
              NULLS LAST)<=3)
19 rows selected.
SQL> SY.