Get Old Value and the new value based on the date

Question

Hi
I have a table called roster created below with following insert statements.
CREATE TABLE ROSTER
ROSTER_EMPLOYEE_DEF_ID NUMBER,
EMPLOYEE_ID NUMBER,
DEFINITION_REGION_CODE NUMBER,
DEFINITION_DISTRICT_CODE NUMBER,
DEFINITION_TERRITORY_CODE NUMBER,
START_DATE DATE,
END_DATE DATE
INSERT INTO ROSTER
(ROSTER_EMPLOYEE_DEF_ID,EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE)
VALUES
(1,299,222,333,444,'1-JUN-2011','30-JUN-2011')
INSERT INTO ROSTER
(ROSTER_EMPLOYEE_DEF_ID,EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE)
VALUES
(2,299,223,334,445,'1-JUL-2011','20-JUL-2011')
INSERT INTO ROSTER
(ROSTER_EMPLOYEE_DEF_ID,EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE)
VALUES
(3,299,224,335,446,'1-AUG-2011','30-AUG-2011')
INSERT INTO ROSTER
(ROSTER_EMPLOYEE_DEF_ID,EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE)
VALUES
(4,300,500,400,300,'1-JUN-2011','20-JUN-2011')
INSERT INTO ROSTER
(ROSTER_EMPLOYEE_DEF_ID,EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE)
VALUES
(5,300,501,401,301,'1-JUL-2011','20-JUL-2011')
In the above table we have columns like
EMPLOYEE_ID,DEFINITION_REGION_CODE,DEFINITION_DISTRICT_CODE,DEFINITION_TERRITORY_CODE,START_DATE,END_DATE
The result i am looking from the above table is based on the EMPLOYEE_ID OF START_DATE AND END_DATE
I need to get OLD_DEFINITION_REGION_CODE and the NEW_DEFINITION_CODE
Similarly OLD_DEFINITION_REGION_CODE and the NEW_DEFINITION_REGION_CODE
and OLD_DEFINITION_TERRITORY_CODE and the NEW_DEFINITION_TERRITORY_CODE
I need to get one row of data for each employee saying old value and new value
for employee 299 there are 3 records it must give the new record which is the latest date i.e start date 1-aug-2011 and end date 30-aug-2011 old record will be
start date 1-jul-2011 and 20-jul-2011
For the above table data i need to get the data as below
EMPLOYEE_ID OLD_DEFINITION_REGION_CODE NEW_DEFINITION_CODE OLD_DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE START_DATE END_DATE
299 223 224 334 335 20-JUL-11 30-AUG-11
300 500 501 400 401 20-JUN-11 20-JUL-11
Please suggest me to get the above result based on the data. Please let me know if my posts are not clear
Thanks
Sudhir

Answer 1

SELECT  EMPLOYEE_ID,
        OLD_DEFINITION_REGION_CODE,
        NEW_DEFINITION_REGION_CODE,
        OLD_DEFINITION_DISTRICT_CODE,
        NEW_DEFINITION_DISTRICT_CODE,
        OLD_DEFINITION_TERRITORY_CODE,
        NEW_DEFINITION_TERRITORY_CODE,
        START_DATE,
        END_DATE
  FROM  (
         SELECT  EMPLOYEE_ID,
                 ROW_NUMBER() OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE DESC) RN,
                 LAG(DEFINITION_REGION_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_REGION_CODE,
                 DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE,
                 LAG(DEFINITION_DISTRICT_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_DISTRICT_CODE,
                 DEFINITION_DISTRICT_CODE NEW_DEFINITION_DISTRICT_CODE,
                 LAG(DEFINITION_TERRITORY_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_TERRITORY_CODE,
                 DEFINITION_TERRITORY_CODE NEW_DEFINITION_TERRITORY_CODE,
                 LAG(END_DATE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) START_DATE,
                 END_DATE
           FROM  ROSTER
  WHERE RN = 1
EMPLOYEE_ID OLD_DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE OLD_DEFINITION_DISTRICT_CODE NEW_DEFINITION_DISTRICT_CODE OLD_DEFINITION_TERRITORY_CODE NEW_DEFINITION_TERRITORY_CODE START_DAT END_DATE
        299                        223                        224                          334                          335                           445                           446 20-JUL-11 30-AUG-11
        300                        500                        501                          400                          401                           300                           301 20-JUN-11 20-JUL-11
SQL>  SY.