Calculate Start and End date in Connect By -- When Hirerchy Changes

Question

/* Formatted on 5/20/2013 9:53:00 AM (QP5 v5.115.810.9015) */
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
Hello , Can some one Please help me or Guide me in calculating Start and End dates for the below logic
I want to calculate the Manager Hirerchy for the given Agent.
Then Below Query is working fine and its giving me the desired results
But when there is a change in the Manager Hirerchy or Manager gets Promoted
Then i need to calculate the start date and end date.
CREATE TABLE PERSON_DTL
  SID                 VARCHAR2(10 BYTE),
  EMP_MGRS_ID         VARCHAR2(10 BYTE),
  START_EFFECTIVE_DT  DATE,
  END_EFFECTIVE_DT    DATE
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M100', 'M107', TO_DATE('05/20/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M101', 'M102', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/18/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('A100', 'M100', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M100', 'M101', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/18/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M107', 'M102', TO_DATE('05/20/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M102', 'M103', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M103', 'M104', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('A101', 'M105', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
Insert into PERSON_DTL
   (SID, EMP_MGRS_ID, START_EFFECTIVE_DT, END_EFFECTIVE_DT)
Values
   ('M105', 'M106', TO_DATE('01/01/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('12/31/9999 00:00:00', 'MM/DD/YYYY HH24:MI:SS'));
COMMIT;
SELECT   CONNECT_BY_ROOT (b.sid) agent_sid,
             TRIM (
                LEADING ',' FROM    SYS_CONNECT_BY_PATH (b.sid, ',')
                                 || ','
                                 || b.emp_mgrs_id
                PATH,
             START_EFFECTIVE_DT Start_dt,
             END_EFFECTIVE_DT End_dt
      FROM   PERSON_DTL b
     WHERE   CONNECT_BY_ISLEAF = 1
START WITH   sid IN ('A101', 'A100')
CONNECT BY   PRIOR b.emp_mgrs_id = b.sid
This is the results that i am getting now.
AGENT_SID    PATH                       START_DT    END_DT
A100    A100,M100,M101,M102,M103,M104    1/1/2010    12/31/9999
A100    A100,M100,M107,M102,M103,M104    1/1/2010    12/31/9999
A101    A101,M105,M106                   1/1/2010    12/31/9999
Results Required
A100    A100,M100,M101,M102,M103,M104    1/1/2010    5/18/2013
A100    A100,M100,M107,M102,M103,M104    5/20/2013   12/31/9999
A101    A101,M105,M106                   1/1/2010    12/31/9999

Answer 1

May be this..
SQL> select agent_sid,max(path) path,max(start_dt) start_dt,
  2         min(end_dt) end_dt
  3  from
  4  (
  5    select agent_sid,path,start_dt,end_dt,
  6           sum(flg) over(order by rn) sm
  7    from
  8    (
  9      select agent_sid,
10             path,
11             start_dt,
12             end_dt,rn,
13             case when path like lag(path) over(order by rn)||'%' then 0 else 1 end flg
14      from
15      (
16        SELECT   CONNECT_BY_ROOT (b.sid) agent_sid,
17                 TRIM (
18                    LEADING ',' FROM    SYS_CONNECT_BY_PATH (b.sid, ',')
19                                     || ','
20                                     || b.emp_mgrs_id
21                 )
22                  PATH,
23                 START_EFFECTIVE_DT Start_dt,
24                 END_EFFECTIVE_DT End_dt,rownum rn
25        FROM   PERSON_DTL b
26        START WITH   sid IN ('A101', 'A100')
27        CONNECT BY   PRIOR b.emp_mgrs_id = b.sid
28      )
29    )
30  )
31  group by agent_sid,sm
32  order by agent_sid;
AGENT_SID  PATH                                     START_DT  END_DT
A100       A100,M100,M101,M102,M103,M104            01-JAN-10 18-MAY-13
A100       A100,M100,M107,M102,M103,M104            20-MAY-13 31-DEC-99
A101       A101,M105,M106                           01-JAN-10 31-DEC-99Edited by: jeneesh on May 20, 2013 7:54 PM
Not thoroughly tested.And not sure whether an easy way exists..