Max amount of planes in the air simultaniously - giving arrival and departuetime

Question

hi!
I use oracle 11g and I have a SQL Server table with a flight field (flightNo) and  two datetime fields (Departuredatetime, Arrivaldatetime).
How is it possible to query the max amout of planes being in the air simultaniously in a certain timeperiode? result should provide the datetime of this maximum also.
Example:
flight55:         |------|
flight67:              |--------------------|
flight69:                  |--|
flight88:                              |-----------|
result:
timestamp     no of planes
09:34             3
sorry I can't provide an insert because I am beginner and have only read access to the database.
thank you so much!

Answer 1

Maybe for a complete solution some Tabibitosan is needed :-)
Otherwise consecutive time slots will be shown as distinct rows.
Let's modify Karthik's example data (flight 1 arrives one our later)
DROP TABLE flight_time_table;
CREATE TABLE flight_time_table
  flight_no  INTEGER
, start_time DATE
, end_time   DATE
ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH:MI:SS AM';
INSERT INTO flight_time_table(flight_no, start_time, end_time)
VALUES (1, '14-JAN-2013 12:00:00 AM', '14-JAN-2013 05:00:00 AM');
INSERT INTO flight_time_table(flight_no, start_time, end_time)
VALUES (2, '14-JAN-2013 02:00:00 AM', '14-JAN-2013 10:00:00 AM');
INSERT INTO flight_time_table(flight_no, start_time, end_time)
VALUES (3, '14-JAN-2013 05:00:00 AM', '14-JAN-2013 06:00:00 AM');
INSERT INTO flight_time_table(flight_no, start_time, end_time)
VALUES (4, '14-JAN-2013 08:00:00 AM', '14-JAN-2013 12:00:00 PM');
COMMIT;
WITH  got_in_air_cnt  AS (
    SELECT    start_time
             ,LEAD (start_time) OVER (ORDER BY start_time)  AS end_time
             ,SUM (SUM (net_change))
                 OVER (ORDER BY start_time)  AS in_air_cnt
    FROM      flight_time_table
    UNPIVOT   (    start_time
              FOR  net_change  IN  ( start_time  AS  1
                                   , end_time    AS -1
    GROUP BY  start_time
,numbered_count AS(
    SELECT  start_time
           ,end_time
           ,in_air_cnt
           ,CASE WHEN start_time <> LAG(end_time,1,DATE '0001-01-01') OVER (ORDER BY start_time)
              OR in_air_cnt <> NVL(LAG(in_air_cnt,1,NULL) OVER (ORDER BY start_time),in_air_cnt)
            THEN
                ROW_NUMBER() OVER (ORDER BY start_time)
            END rn
    FROM    got_in_air_cnt
,grouped_count AS(
    SELECT  start_time
           ,end_time
           ,in_air_cnt
           ,MAX(rn) OVER (ORDER BY start_time) grp
    FROM    numbered_count
,got_rnk AS (
    SELECT  MIN(start_time) start_time
           ,MAX(end_time) end_time
           ,in_air_cnt
           ,RANK () OVER (ORDER BY  in_air_cnt  DESC)  AS rnk
    FROM    grouped_count
    GROUP BY grp
            ,in_air_cnt
SELECT  start_time
       ,end_time
       ,in_air_cnt
FROM    got_rnk
WHERE   rnk  = 1
ORDER BY  start_time
START_TIME               END_TIME                 IN_AIR_CNT
14-JAN-2013 02:00:00 AM  14-JAN-2013 06:00:00 AM           2
14-JAN-2013 08:00:00 AM  14-JAN-2013 10:00:00 AM           2
I use the max-on-case-row-number version of Tabibitosan from About Oracle: Tabibitosan
Regards
Marcus