Query help first two rows

Question

i need to sort desc order by date and need to take two rows only
id date
1 1/2/1994
2 2/2/2000
3 1/5/88
4 6/5/2006
i need out put like this
id date
4 6/5/2006
2 2/2/2000
plz give query with good perfomence thanks

Answer 1

You can use any one of the below query which performs better for you
SQL> with t
  2  as
  3  (
  4  select 1 id,to_date('1/2/1994','dd/mm/yyyy') dt from dual
  5  union all
  6  select 2,to_date('2/2/2000','dd/mm/yyyy') from dual
  7  union all
  8  select 3,to_date('1/5/88','dd/mm/yyyy') from dual
  9  union all
10  select 4,to_date('6/5/2006','dd/mm/yyyy') from dual
11  )
12  select * from
13  (
14  select * from t
15  order by 2 desc
16  )
17  where rownum <=2
18  /
        ID DT
         4 06-MAY-06
         2 02-FEB-00
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=9 Card=2 Bytes=24)
   1    0   COUNT (STOPKEY)
   2    1     VIEW (Cost=9 Card=4 Bytes=48)
   3    2       SORT (ORDER BY STOPKEY) (Cost=9 Card=4 Bytes=48)
   4    3         VIEW (Cost=8 Card=4 Bytes=48)
   5    4           UNION-ALL
   6    5             FAST DUAL (Cost=2 Card=1)
   7    5             FAST DUAL (Cost=2 Card=1)
   8    5             FAST DUAL (Cost=2 Card=1)
   9    5             FAST DUAL (Cost=2 Card=1)
Statistics
          1  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
        416  bytes sent via SQL*Net to client
        496  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          2  rows processed
SQL> with t
  2  as
  3  (
  4  select 1 id,to_date('1/2/1994','dd/mm/yyyy') dt from dual
  5  union all
  6  select 2,to_date('2/2/2000','dd/mm/yyyy') from dual
  7  union all
  8  select 3,to_date('1/5/88','dd/mm/yyyy') from dual
  9  union all
10  select 4,to_date('6/5/2006','dd/mm/yyyy') from dual
11  )
12  select id,dt
13  from
14  (
15  select id,dt,row_number() over(order by dt desc) rn from t
16  order by 2 desc
17  )
18  where rn <=2
19  /
        ID DT
         4 06-MAY-06
         2 02-FEB-00
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=8 Card=4 Bytes=100
   1    0   VIEW (Cost=8 Card=4 Bytes=100)
   2    1     WINDOW (SORT PUSHED RANK) (Cost=8 Card=4 Bytes=48)
   3    2       VIEW (Cost=8 Card=4 Bytes=48)
   4    3         UNION-ALL
   5    4           FAST DUAL (Cost=2 Card=1)
   6    4           FAST DUAL (Cost=2 Card=1)
   7    4           FAST DUAL (Cost=2 Card=1)
   8    4           FAST DUAL (Cost=2 Card=1)
Statistics
          1  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
        416  bytes sent via SQL*Net to client
        496  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          1  sorts (memory)
          0  sorts (disk)
          2  rows processed