SQL Select 1 record from each department

Question

assume emp table
1- i want to retrive 1 employee from each department
2- 2 from each
3- total 20 records 1st employee from 1st dept, 2nd from 2nd, 3rd from 3rd, 4th from 1st , 5th from 2nd and so on
Edited by: Fakhr-e-Alam on Aug 10, 2011 3:20 AM

Answer 1

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This is how to do the first one: you shoudl be able to figure out the others from here.
SQL> select e.*
  2  from emp e
  3  where (empno, 1) in
  4      ( select x.empno
  5               , row_number() over (partition by x.deptno
  6                                    order by x.hiredate )
  7        from emp x )
  8  order by e.deptno
  9  /
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7782 BOEHMER    MANAGER         7839 09-JUN-81       2450                    10
      7369 CLARKE     CLERK           7902 17-DEC-80        800                    20
      7499 VAN WIJK   SALESMAN        7698 20-FEB-81       1600        300         30
      8101 PSMITH                          03-DEC-10                               40
      8060 VERREYNNE  PLUMBER         8061 08-APR-08       4000                    50
SQL>In this case, the employees are ordered on the basis of HIREDATE, so the longest serving employees are selected from each department. Other definitions of "first" will require different sorting criteria. You know your own business rules.
Cheers, APC
Edited by: APC on Aug 10, 2011 10:33 AM