Minimum hiredate in emp table

Question

Hi,
There is an emp table, which a column hiredate(date). I want to get the record with minimum hiredate and using this query.
SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for Solaris: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
SQL> with t as
  2  (select 'A' ename, 1 enum, '1-Oct-2008' hiredate from dual union all
  3  select 'B', 2, '1-Jan-2002' from dual union all
  4  select 'C', 3, '1-Mar-2008' from dual)
  5  select * from t
  6  where hiredate = (select min(hiredate) from t);
E       ENUM HIREDATE
B          2 1-Jan-2002
SQL> Is there any other way to do it, without using subquery?
Regards,
Ritesh

Answer 1

Centinul:
Are you sure?
I added another record with the "lowest" hiredate. The OP's original version:
SQL> with t as
  2     (select 'A' ename, 1 enum, '1-Oct-2008' hiredate from dual union all
  3      select 'B', 2, '1-Jan-2002' from dual union all
  4      select 'C', 3, '1-Mar-2008' from dual union all
  5      select 'D', 4, '1-Jan-2002' from dual)
  6  select * from t
  7  where hiredate = (select min(hiredate) from t);
E       ENUM HIREDATE
B          2 1-Jan-2002
D          4 1-Jan-2002Your version:
SQL> with t as
  2     (select 'A' ename, 1 enum, '1-Oct-2008' hiredate from dual union all
  3      select 'B', 2, '1-Jan-2002' from dual union all
  4      select 'C', 3, '1-Mar-2008' from dual union all
  5      select 'D', 4, '1-Jan-2002' from dual)
  6  SELECT  MIN(ENUM)       KEEP (DENSE_RANK FIRST ORDER BY HIREDATE)       AS ENUM,
  7          MIN(HIREDATE)   KEEP (DENSE_RANK FIRST ORDER BY HIREDATE)       AS HIREDATE
  8  FROM    t;
      ENUM HIREDATE
         2 1-Jan-2002Your version also misses the ename column which the OP has, so yours needs to be more like:
SQL> with t as
  2     (select 'A' ename, 1 enum, '1-Oct-2008' hiredate from dual union all
  3      select 'B', 2, '1-Jan-2002' from dual union all
  4      select 'C', 3, '1-Mar-2008' from dual union all
  5      select 'D', 4, '1-Jan-2002' from dual)
  6  SELECT  ename, MIN(ENUM) KEEP (DENSE_RANK FIRST ORDER BY HIREDATE) AS ENUM,
  7          MIN(HIREDATE) KEEP (DENSE_RANK FIRST ORDER BY HIREDATE) AS HIREDATE
  8  FROM    t
  9  GROUP BY ename;
E       ENUM HIREDATE
A          1 1-Oct-2008
B          2 1-Jan-2002
C          3 1-Mar-2008
D          4 1-Jan-2002Which kind of defeats the purpose :-)
Top replicate the behaviour of the OP's query:
SQL> with t as
  2     (select 'A' ename, 1 enum, '1-Oct-2008' hiredate from dual union all
  3      select 'B', 2, '1-Jan-2002' from dual union all
  4      select 'C', 3, '1-Mar-2008' from dual union all
  5      select 'D', 4, '1-Jan-2002' from dual)
  6  select *
  7  from (SELECT t.*, DENSE_RANK() OVER(ORDER BY hiredate) rn
  8        FROM t)
  9  where rn = 1
E       ENUM HIREDATE           RN
B          2 1-Jan-2002          1
D          4 1-Jan-2002          1It still has a sub-query, but it is only one pass through the table which I took to be the point.
John