Pick the last row returned from query

Question

hii...
i have a query thats returns...
SQL> WITH tbl_zone AS (
  2       SELECT to_date('02/03/2010', 'DD/MM/YYYY') close_date FROM dual UNION ALL
  3       SELECT to_date('03/03/2010', 'DD/MM/YYYY') FROM dual UNION ALL
  4       SELECT to_date('04/03/2010', 'DD/MM/YYYY') FROM dual UNION ALL
  5       SELECT to_date('09/03/2010', 'DD/MM/YYYY') FROM dual UNION ALL
  6       SELECT to_date('11/03/2010', 'DD/MM/YYYY') FROM dual)
  7    SELECT  TRUNC(close_date, 'IW') close_date
  8   from tbl_zone t
  9   ORDER BY 1 DESC;
CLOSE_DATE
08/03/2010
08/03/2010
01/03/2010
01/03/2010
01/03/2010i want the query to return just i row and that should be the greatest date
in the above example
the query should return single row out of the 2 greatest dates, 08/03/2010.
CLOSE_DATE
08/03/2010Please any one suggest...

Answer 1

How about row_number()
SQL> with tbl_zone as (
  2       select to_date('02/03/2010', 'dd/mm/yyyy') close_date from dual union all
  3       select to_date('03/03/2010', 'dd/mm/yyyy') from dual union all
  4       select to_date('04/03/2010', 'dd/mm/yyyy') from dual union all
  5       select to_date('09/03/2010', 'dd/mm/yyyy') from dual union all
  6       select to_date('11/03/2010', 'dd/mm/yyyy') from dual
  7       )
  8  --
  9  --
10  --
11  select close_date
12  from ( select trunc(close_date, 'iw') close_date
13         ,      row_number() over ( order by close_date desc)  rn
14         from   tbl_zone t
15       )      
16  where rn=1;
CLOSE_DATE
08-03-2010 00:00:00