Assign Month within a date range (by most days in a given month)

Question

I have a begin and end date, sample data as such
select to_date('01-13-12','mm-dd-yy') from_dt,
to_date('02-23-12','mm-dd-yy') to_dt
from dual
union all
select to_date('03-15-2012','mm-dd-yy') from_dt,
to_date('04-16-2012','mm-dd-yy') to_dt
from dual
union all
select to_date('05-13-2012','mm-dd-yy') from_dt,
to_date('07-23-2012','mm-dd-yy') to_dt
from dual
How do I assign a month by the most days in a month within that date range? Sometimes the date range might have the exact same amount of days in a month (like 3/15/2012 has 16 days and 4/16/2012 has 16 days). In this case, I want the earlier month (march).
So from the sample data:
01/13/2012, 02/23/2012, February
03/15/2012, 04/16/2012, March
05/13/2012, 07/23/2012, June
Thanks
Edited by: user4422426 on Mar 1, 2012 5:15 PM

Answer 1

Hi,
Here's one way:
WITH     cntr          AS
     SELECT     LEVEL - 1     AS n
     FROM     (
               SELECT      1 + MAX (to_dt - from_dt)     AS max_day_cnt
               FROM     table_x
     CONNECT BY     LEVEL     <= max_day_cnt
,     got_r_num     AS
     SELECT     x.from_dt, x.to_dt
     ,     TRUNC (x.from_dt + c.n, 'MONTH')     AS month
     ,     count (*)                    AS cnt
     ,     ROW_NUMBER () OVER ( PARTITION BY  from_dt, to_dt
                         ORDER BY        COUNT (*)     DESC
                         ,             TRUNC (x.from_dt + c.n, 'MONTH')
                       )     AS r_num
     FROM       cntr     c
     JOIN       table_x  x  ON  c.n  <= x.to_dt - x.from_dt
     GROUP BY  x.from_dt, x.to_dt
     ,       TRUNC (x.from_dt + c.n, 'MONTH')
SELECT     from_dt, to_dt
,     TO_CHAR (month, 'Mon YYYY')     AS mon
,     cnt
FROM     got_r_num
WHERE     r_num     = 1
;Thanks for posting code to create the same data. Please test your code before you post it: you got the order of arguments to TO_DATE reversed.