Create a table with all the months between two dates

Question

Hi all,
I have a purchase table recording individual purchases. One of the fields is my Date field (date of purchase).
I would like to create a table 'All_months' with two entries ('month_no' and 'month') which will be based on the first and last date in the purchase table. Assuming the first purchase recorded in my purchase table was on the 12th of January 2008, the table should have the following structure:
month_no month
1 12JAN2008
2 12FEB2008
3 12MAR2008
It should continue in this fashion up-to the month where the last purchase was recorded.
I have been struggling with creating the query that would do that for days now and can't find anything when asking Mr Google.
Thanks,
Chris

Answer 1

Welcome to the forum!
Here's one way:
CREATE TABLE     all_months
AS
SELECT     LEVEL                    AS month_no
,     ADD_MONTHS ( first_date
             , LEVEL - 1
             )               AS month     
FROM     (
          SELECT     MIN (date_of_purchace)     AS first_date
          ,     MAX (date_of_putchase)     AS last_date
          FROM     purchase
CONNECT BY     LEVEL <= 1 + MONTHS_BETWEEN ( TRUNC (last_date,  'MONTH')
                             , TRUNC (first_date, 'MONTH')
;Do you really need a table like this? Every time you change the data in the purchase table, you won't know if all_months is still accurate or not. You can derive all_months in a sub-query every time you need it, or make all_months a view instead of a table.
Edited by: Frank Kulash on Jun 14, 2012 5:57 AM