Need help for sql statement

Question

Hi,
Need help to write sql statement.
create table t_dt ( dt_start date, dt_end date, amount number);
insert into t_dt values('1-Jan-10','10-Feb-10',12);
insert into t_dt values('11-Feb-10','10-Mar-10',10);
insert into t_dt values('11-Mar-10','20-Apr-10',8);
insert into t_dt values('21-Apr-10','28-Jun-10',10);
insert into t_dt values('29-Jun-10','20-Sep-10',10);
insert into t_dt values('21-Sep-10','10-Oct-10',10);
insert into t_dt values('11-Oct-10','31-Dec-10',8);
insert into t_dt values('1-Jan-11','10-Feb-11',8);
insert into t_dt values('11-Feb-11','10-Mar-11',7);
insert into t_dt values('11-Mar-11','20-Apr-11',6);
insert into t_dt values('21-Apr-11','28-Jun-11',6);
insert into t_dt values('29-Jun-11','20-Sep-11',6);
insert into t_dt values('21-Sep-11','10-Oct-11',4);
insert into t_dt values('11-Oct-11','31-Dec-11',8);
Result should be like below..
dt_start     dt_end     Amount
1-Jan-10     10-Feb-10     12
11-Feb-10     10-Mar-10     10
11-Mar-10     20-Apr-10     8
21-Apr-10     10-Oct-10     10
11-Oct-10     10-Feb-11     8
11-Feb-11     10-Mar-11     7
11-Mar-11     20-Sep-11     6
21-Sep-11     10-Oct-11     4
11-Oct-11     31-Dec-11     8
Just to explain the example, take a row with start date as 21-Apr-10 in the above insert statements, since it has the same amount for next two rows (i.e. with start date '29-Jun-10' and '21-Sep-10') these 3 rows should be converted to represent only 1 row in the result and the start date and end date should be changed per the result shown above.
Thanks.

Answer 1

Hello
I think this gives yuo what you need....
SELECT
    MIN(dt_start),
    MAX(dt_end),
    amount
FROM
    (   SELECT
            dt_start,
            dt_end,
            MAX(marker) OVER(ORDER BY dt_start) marker,
            amount
        FROM
                Select
                    dt_start,
                    dt_end,
                    amount,
                    CASE
                        WHEN LAG(amount) OVER(ORDER BY dt_start) <> amount THEN
                            ROW_NUMBER() OVER(ORDER BY dt_start)
                    END marker
                from t_dt
GROUP BY
     amount,
     marker
order by     
     MIN(dt_start)
MIN(DT_START)        MAX(DT_END)              AMOUNT
01-JAN-2010 00:00:00 10-FEB-2010 00:00:00         12
11-FEB-2010 00:00:00 10-MAR-2010 00:00:00         10
11-MAR-2010 00:00:00 20-APR-2010 00:00:00          8
21-APR-2010 00:00:00 10-OCT-2010 00:00:00         10
11-OCT-2010 00:00:00 10-FEB-2011 00:00:00          8
11-FEB-2011 00:00:00 10-MAR-2011 00:00:00          7
11-MAR-2011 00:00:00 20-SEP-2011 00:00:00          6
21-SEP-2011 00:00:00 10-OCT-2011 00:00:00          4
11-OCT-2011 00:00:00 31-DEC-2011 00:00:00          8
9 rows selected.HTH
David
Edited by: Bravid on Feb 23, 2012 12:08 PM
Beaten to it by Frank! :-)