Find unique row with max func

Question

I am really stupid of this right now. Have not tried the regular SQL for long time, so my question is that I have a table- Cost
A     B     C     D     E     F
0002     6002     5     55     68.35     6.12
0003     6003     5     99.26     89.33     8.23
0004     6004     5     78.85     4.4     7.42
0004     6004     6     78.85     8.1     1.7
0004     6004     7     78.85     70.9     6.73
0005     6005     5     49.88     76.1     68.53
0005     6005     6     49.88     93.7     18.57
0005     6005     7     49.88     255.7     63
How can I get the column E and F, when I want to get the row with highest order in C as result in
A     B     C     D     E     F
0002     6002     5     55     68.35     6.12
0003     6003     5     99.26     89.33     8.23
0004     6004     7     78.85     70.9     6.73
0005     6005     7     49.88     255.7     63
I used the max () and group by in query as
select A, B, max(C), D
from cost
group by A,B,D
If I added the max(E) and max(F) in the SELECT, I got correct row in E but not the F.
Please help me out. Thanks.

Answer 1

an alternative using analytic fiunctions would be:
select "A","B",max("C"),"D","E","F" from
(select "A","B","C",last_value("D") over (partition by "A","B" order by
"A","B","C" rows between unbounded preceding and unbounded following) "D",
last_value("E") over (partition by "A","B" order by
"A","B","C" rows between unbounded preceding and unbounded following) "E",
last_value("F") over (partition by "A","B" order by
"A","B","C" rows between unbounded preceding and unbounded following) "F"
from test1)
group by "A","B","D","E","F"
order by "A","B"
this appears to give a better plan on the test data but you would want to test with a larger volume, we have reduced to numbet of buffer gets but added two sorts currently these fit in memory but you may find with a larger dataset these result in disk sorts.
Chris
Autotrace output:
SQL> select * from test1 where "A"||B||"C" in (select "A"||B||Z from (select "A", B, max("C") Z from test1 group by "A",B));
A    B             C          D          E          F
0002 6002          5         55      68.35       6.12
0003 6003          5      99.26      89.33       8.23
0004 6004          7      78.85       70.9       6.73
0005 6005          7      49.88      255.7         63
Execution Plan
Plan hash value: 2706139598
| Id  | Operation             | Name     | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT      |          |     1 |    50 |     8  (25)| 00:00:01 |
|*  1 |  HASH JOIN            |          |     1 |    50 |     8  (25)| 00:00:01 |
|   2 |   TABLE ACCESS FULL   | TEST1    |     8 |   192 |     3   (0)| 00:00:01 |
|   3 |   VIEW                | VW_NSO_1 |     8 |   208 |     4  (25)| 00:00:01 |
|   4 |    HASH UNIQUE        |          |     8 |   104 |     4  (25)| 00:00:01 |
|   5 |     HASH GROUP BY     |          |     8 |   104 |     4  (25)| 00:00:01 |
|   6 |      TABLE ACCESS FULL| TEST1    |     8 |   104 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - access("$nso_col_1"="A"||"B"||TO_CHAR("C"))
Statistics
          0  recursive calls
          0  db block gets
         64  consistent gets
          0  physical reads
          0  redo size
        795  bytes sent via SQL*Net to client
        381  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          4  rows processed
SQL>
SQL> select "A","B",max("C"),"D","E","F" from
  2  (select  "A","B","C",last_value("D") over (partition by "A","B" order by
  3  "A","B","C" rows between unbounded preceding and unbounded following) "D",
  4  last_value("E") over (partition by "A","B" order by
  5  "A","B","C" rows between unbounded preceding and unbounded following) "E",
  6  last_value("F") over (partition by "A","B" order by
  7  "A","B","C" rows between unbounded preceding and unbounded following) "F"
  8  from test1)
  9  group by "A","B","D","E","F"
10  order by "A","B";
A    B      MAX("C")          D          E          F
0002 6002          5         55      68.35       6.12
0003 6003          5      99.26      89.33       8.23
0004 6004          7      78.85       70.9       6.73
0005 6005          7      49.88      255.7         63
Execution Plan
Plan hash value: 3359524756
| Id  | Operation            | Name  | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |       |     8 |   496 |     5  (40)| 00:00:01 |
|   1 |  SORT GROUP BY       |       |     8 |   496 |     5  (40)| 00:00:01 |
|   2 |   VIEW               |       |     8 |   496 |     4  (25)| 00:00:01 |
|   3 |    WINDOW SORT       |       |     8 |   192 |     4  (25)| 00:00:01 |
|   4 |     TABLE ACCESS FULL| TEST1 |     8 |   192 |     3   (0)| 00:00:01 |
Statistics
          0  recursive calls
          0  db block gets
          7  consistent gets
          0  physical reads
          0  redo size
        802  bytes sent via SQL*Net to client
        381  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
          4  rows processed
SQL>