Check if a license exists for at least one day in each month

Question

How to check if a license exists for at least one day in each month for a given period ? Example : If we have a review period from Jan 25 2009 to Aug 15 2009. How to check if there is license for at lease one day in every month.

Answer 1

Hi,
Welcome to the forum!
(1) construct a table or result set that has one row per month in the review period. [This thread|http://forums.oracle.com/forums/thread.jspa?messageID=3651350?] has a similar problem.
(2) outer-join your actual data to that result set
(3) use the aggreagate COUNT (x) function (where x is some column from your table) to see if there were any matches in each month. GROUP BY months.
For a more specific answser, ask a more specific question.
Post a little sample data (CREATE TABLE and INSERT statements), and the results you want from that data.
It never hurts to say what version of Oracle you're using.
Edited by: Frank Kulash on Jul 28, 2009 1:54 PM
Maybe something like:
WITH  all_months  AS
     SELECT     ADD_MONTHS ( TRUNC ( &period_begin_date
                            , 'MM'
                  , LEVEL - 1
                  )         AS month_date
     FROM    dual
     CONNECT BY  LEVEL <= 1 + CEIL ( MONTHS_BETWEEN ( &period_end_date
                                                      , &period_begin_date
SELECT       m.month_date
,       CASE  COUNT (l.license_date)
            WHEN  0  THEN  'Nothing this month'
                      ELSE  'Some licenses issued'
       END     AS summary_txt
FROM            all_months     m
LEFT OUTER JOIN     license_table     l     ON  m.month_date     = TRUNC (l.license_date, 'MM')
                                 AND l.license_date     BETWEEN  &period_begin_date
                                            AND      &period_end_date
GROUP BY  m.month_date
ORDER BY  m.month_date
;Untested