Help required for dynamic quarter calculation

Question

I have a requirement, where the user will have the liberty to choose his self defined Quarter and the report output will be grouped based on what he selects.
The data in the table is at daily grain.
So ,if the user selects date as 1st April and number of quarters as 2.
The report should show the data aggregated for previous 2 quarters where 1st April is the start date.
i.e.Feb-March-April as Q2
and Nov-Dec-Jan as Q1
Please suggest how to implement this.
Best Regards,
Sud

Answer 1

Hi,
Welcome to the forum!
Whenever you have a question, please post a little sample data (CREATE TABLE and INSERT statements) for all the tables involved, so the people who want to help you can re-create the problem and test their ideas. Also post the results you want from that data, and an explanation of how you get those results from that data.
If the problem involves parameters (such as the number of quarters you want, and the starting point of one of the quarters) then post a few sets of parameters, and the results you want from the same sample data for each set.
Explain, using specific examples, how you get those results from that data.
Always say what version of Oracle you're using (e.g. 11.2.0.2.0).
See the forum FAQ {message:id=9360002}
Here's one way you can pass the set the number of quarters, and the starting date of the last quarter wanted:
WITH   params      AS
     SELECT  TO_DATE ( '01-Apr-2012'     -- Beginning of last quarter
               , 'DD-Mon-YYYY'
               )     AS s_date
     ,     5          AS num_quarters
     FROM     dual
,     quarters_wanted         AS
     SELECT  ADD_MONTHS ( start_date)
                  , 3 * (1 - LEVEL)
                  )   AS start_dt
     ,     ADD_MONTHS ( start_date)
                  , 3 * (2 - LEVEL)
                  )   AS end_dt
     FROM     params
     CONNECT BY     LEVEL <= num_quarters
SELECT       q.start_date
,       COUNT (*)     AS num_rows
FROM       quarters_wanted  a
JOIN       your_table        t  ON  t.date_column  >= q.start_date
                       AND t.date_coplumn <  q.end_date
GROUP BY  q.start_date
;No matter what date you pick (it doesn't have to be the beginning of a month) or how many quarters you want, you only have to change 2 lines in the params sub-query.
If you want to include quarters that have no data in your table (with a COUNT of 0) then change the inner JOIN in the main query to a LEFT OUTER JOIN.