Help PLEASE, I think with MERGE--

Question

Hi, am trying to update a table where the dates and IDs are 2 or more rows. What I'd like to do is, if date2 on row1 is within 24 hours of date1 on row2, then the date2(row2) updates date2(row1) and the row2 gets totally deleted (see merged result example below).
For example,
logid date1 date2
1111111 01/01/2007 01/03/2007
1111111 01/03/2007 02/15/2007
1111111 01/01/2007 02/15/2007 --- merged result
I've tried rowid's and rownums and merges, subqueries too, but I just don't thinkk I'm getting it right. Any help?
Thanks,
Chris Adams

Answer 1

Nicolas is unbeatable ;)
SQL> CREATE TABLE t (logid INTEGER, date1 DATE, date2 DATE)
Table created.
SQL> INSERT INTO t
     VALUES (1111111, DATE '2007-01-01', DATE '2007-01-03')
1 row created.
SQL> INSERT INTO t
     VALUES (1111111, DATE '2007-01-03', DATE '2007-02-15')
1 row created.
SQL> MERGE INTO t t1
   USING (SELECT ROWID,
                 logid,
                 date1,
                 date2,
                 CASE
                    WHEN date2 BETWEEN LEAD (date1) OVER (ORDER BY date1) - 1
                                   AND LEAD (date1) OVER (ORDER BY date1) + 1
                       THEN LEAD (date2) OVER (ORDER BY date1)
                 END x
            FROM t) t2
   ON (t1.ROWID = t2.ROWID)
   WHEN MATCHED THEN
      UPDATE
         SET date2 = t2.x
      DELETE
         WHERE date2 IS NULL
Merge successfully completed.
SQL> SELECT *
  FROM t
                                             LOGID DATE1     DATE2   
                                           1111111 01-JAN-07 15-FEB-07