I guess something like:

SELECT min_start_date, MAX(end_date)
FROM (
   SELECT
     start_date, end_date,
     MAX(CASE WHEN start_date <= max_end_date + 1 day
         THEN NULL ELSE start_date END)
       OVER (ORDER BY start_date, end_date
             ROWS UNBOUNDED PRECEDING)
   FROM (
     SELECT
        start_date, end_date,
         MAX(end_date) OVER (
                ORDER BY start_date, end_date
                ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
         )
     FROM events
  ) T1 (start_date, end_date, max_end_date)
) T2 (start_date, end_date, min_start_date)
GROUP BY min_start_date
ORDER BY min_start_date;

should work

/Lennart

This is my trial. I added data which are included in another row's
range.

INSERT INTO Events
VALUES ('Apple Eating', '2009-01-01', '2009-01-02')
    , ('Apple Eating', '2009-01-03', '2009-01-05')
    , ('Apple Eating', '2009-01-04', '2009-01-10')
    , ('Apple Eating', '2009-01-05', '2009-01-06')
    , ('Apple Eating', '2009-01-08', '2009-01-09')
    , ('Apple Eating', '2009-01-11', '2009-01-12')
    , ('Apple Eating', '2009-02-01', '2009-02-07')
    , ('Apple Eating', '2009-03-01', '2009-03-07')
    , ('Apple Eating', '2009-03-03', '2009-03-05')
    , ('Apple Eating', '2009-04-01', '2009-04-03')
    , ('Apple Eating', '2009-04-04', '2009-04-05')
    , ('Apple Eating', '2009-04-04', '2009-04-06')
;

------------------------- Commands Entered -------------------------
WITH Flagged_Events AS (
SELECT event_id, start_date, end_date
    , CASE
      WHEN (pre_end_date   < start_date - 1 DAYS
            OR
            pre_end_date IS NULL)
       AND (fol_start_date > end_date   + 1 DAYS
            OR
            fol_start_date IS NULL
            OR
            fol_end_date   < end_date)           THEN
           'Only'
      WHEN (pre_end_date   < start_date - 1 DAYS
            OR
            pre_end_date IS NULL)
       AND fol_start_date <= end_date   + 1 DAYS THEN
           'Begin'
      WHEN pre_end_date   >= start_date - 1 DAYS
       AND pre_end_date    < end_date
       AND (fol_start_date > end_date   + 1 DAYS
            OR
            fol_start_date IS NULL
            OR
            fol_end_date   < end_date)           THEN
           'End'
      ELSE 'Middle'
      END  AS Flag
 FROM (SELECT event_id, start_date, end_date
            , MAX(end_date)   OVER(PARTITION BY event_id
                                       ORDER BY start_date, end_date
                                   ROWS BETWEEN UNBOUNDED PRECEDING
                                            AND 1 PRECEDING
                                  ) pre_end_date
            , MIN(end_date)   OVER(PARTITION BY event_id
                                       ORDER BY start_date, end_date
                                   ROWS BETWEEN 1 FOLLOWING
                                            AND UNBOUNDED FOLLOWING
                                  ) fol_end_date
            , MIN(start_date) OVER(PARTITION BY event_id
                                       ORDER BY start_date, end_date
                                   ROWS BETWEEN 1 FOLLOWING
                                            AND UNBOUNDED FOLLOWING
                                  ) fol_start_date
         FROM Events
     ) R
)
SELECT event_id, start_date
    , CASE Flag
      WHEN 'Only' THEN
           end_date
      ELSE new_end_date
      END  AS end_date
 FROM (SELECT event_id, start_date, end_date, Flag
            , MAX(end_date) OVER(PARTITION BY event_id
                                     ORDER BY start_date, end_date
                                 ROWS BETWEEN CURRENT ROW
                                          AND 1 FOLLOWING
                                ) new_end_date
         FROM (SELECT event_id, start_date, end_date, Flag
                    , MAX(Flag) OVER(PARTITION BY event_id
                                         ORDER BY start_date,
end_date
                                     ROWS BETWEEN 1 FOLLOWING
                                              AND 1 FOLLOWING
                                    ) fol_Flag
                 FROM Flagged_Events
                WHERE Flag <> 'Middle'
              ) Q
        WHERE Flag <> 'End'
           OR Flag =  'End' AND (fol_Flag <> 'End' OR fol_Flag IS
NULL)
      ) R
WHERE Flag <> 'End'
ORDER BY
      event_id, start_date;
--------------------------------------------------------------------

EVENT_ID                  START_DATE END_DATE
------------------------- ---------- ----------
Apple Eating              2009-01-01 2009-01-12
Apple Eating              2009-02-01 2009-02-07
Apple Eating              2009-03-01 2009-03-07
Apple Eating              2009-04-01 2009-04-06
Pie Eating                2009-01-01 2009-01-07
Pie Eating                2009-02-01 2009-02-07

 6 record(s) selected.

Joe,

This only works if some date record in the cal_date table exists within the
date range of each and every row for an event.  Otherwise you will not see
the entire range of the event, only the range spanned by cal_date records.
If that's what you want, it's fine.  However, if, instead, the request is to
fetch the entire range of dates for an event that will include a given
single date (or small date range).  That would require one to push the date
matching into a sub-query IB.

Art S. Kagel

I know Rick from our time on ANSI X3H2 together and I used some of his
material in one of my other books.  I am trying to do an updated
version of it, with some of the new SQL-99 and SQL-2003 stuff.  That
is why I am posting in newgroups that attract smart programmers :)

I did not know about Zimanyi's stuff; thanks!