For fetching records under id

Question

I am having a master table with data like
EMPNO     DEPTID HEAD
1     IT     0
2     IT     1
3     IT     1
4     IT     1
5     IT     2
6     IT     2
7     IT     4
8     IT     4
9     IT     5
10     IT     5
11     HR     0
12     HR     1
13     HR     1
14     HR     1
Query to findout all empno under the head by passing head empno
means if i am passing empno as 1 then
LIST SHOULD BE
2,3,4,5,6,7,8,9,10
If empno is 2 then
5,6,9,10
kindly help for the same

Answer 1

Are you looking for something like this...
WITH tab AS
  ( SELECT 1 empno, 'IT' deptid, 0 head FROM dual
UNION ALL
      SELECT 2 empno, 'IT' deptid, 1 head FROM dual
UNION ALL
      SELECT 3 empno, 'IT' deptid, 1 head FROM dual
UNION ALL
      SELECT 4 empno, 'IT' deptid, 1 head FROM dual
UNION ALL
      SELECT 5 empno, 'IT' deptid, 2 head FROM dual
UNION ALL  
   SELECT 6 empno, 'IT' deptid, 2 head FROM dual
UNION ALL
      SELECT 7 empno, 'IT' deptid, 4 head FROM dual
UNION ALL
      SELECT 8 empno, 'IT' deptid, 4 head FROM dual
UNION ALL
      SELECT 9 empno, 'IT' deptid, 5 head FROM dual
UNION ALL
      SELECT 10 empno, 'IT' deptid, 5 head FROM dual
UNION ALL
      SELECT 11 empno, 'HR' deptid, 0 head FROM dual
UNION ALL  
   SELECT 12 empno, 'HR' deptid, 1 head FROM dual
UNION ALL  
   SELECT 13 empno, 'HR' deptid, 1 head FROM dual
UNION ALL
      SELECT 14 empno, 'HR' deptid, 1 head FROM dual
SELECT ltrim(sys_connect_by_path(empno,','),',') lst
   FROM
  (SELECT t.*,
    row_number() over (order by empno ) rnum
     FROM
    (SELECT connect_by_root empno root,
      empno
       FROM tab
      CONNECT BY prior empno=head
      START WITH empno      =1 and deptid='IT'--change empno to 2 here for second case
    ) t
    WHERE t.empno!=t.root
  WHERE connect_by_isleaf=1
  CONNECT BY prior rnum  =rnum-1
  START WITH rnum        =1Ravi Kumar