Question

I have a query which I run on a table TXN_DEC(id, resourceid, usersid, date, eventdesc) which return distinct count of users for a given date-range and resourceid, group by date and eventdesc (each resource can have 4 to 5 eventdesc)

if there is no value of distinct users count on a date in the range, for an eventdesc, then it skips that date row in the resultset.

I need to have all date rows in my resultset or collection such that if there is no value of count for a date,eventdesc combination, then its value is set to 0 but that date still exists in the collection..

How do I go about getting such a collection

I know getting the final dataset entirely from the query result would be too complicated,
but I can use collections in groovy to modify and populate my map/list to get the data in the required format

something similar to following: if

input date range = 5th Feb to 3 March 2011

      DataMap = [dateval: '02/05/2011' eventdesc: 'Read' dist_ucnt: 23,
                 dateval: '02/06/2011' eventdesc: 'Read' dist_ucnt: 23,
                 dateval: '02/07/2011' eventdesc: 'Read' dist_ucnt: 0,  -> this row was not present in query resultset, but row exists in the map with value 0
                 ....and so on till 3 march 2011 and then whole range repeated for each eventdesc
                     ] 

Answer 1

If you want all dates (including those with no entries in your TXN_DEC table) for a given range, you could use Oracle to generate your date range and then use an outer join to your existing query. Then you would just need to fill in null values. Something like:

select 
    d.dateInRange as dateval,
    'Read' as eventdesc,
    nvl(td.dist_ucnt, 0) as dist_ucnt
from (
    select 
        to_date('02-FEB-2011','dd-mon-yyyy') + rownum - 1 as dateInRange
    from all_objects
    where rownum <= to_date('03-MAR-2011','dd-mon-yyyy') - to_date('02-FEB-2011','dd-mon-yyyy') + 1
) d
left join (
    select 
        date,
        count(distinct usersid) as dist_ucnt
    from
        txn_dec
    where eventDesc = 'Read'
    group by date 
) td on td.date = d.dateInRange

That’s my purely Oracle solution since I’m not a Groovy guy (well, actually, I am a pretty groovy guy…)

EDIT: Here’s the same version wrapped in a stored procedure. It should be easy to call if you know the API….

create or replace procedure getDateRange (
    p_begin_date IN DATE, 
    p_end_date IN DATE, 
    p_event IN txn_dec.eventDesc%TYPE,
    p_recordset OUT SYS_REFCURSOR)
AS
BEGIN
    OPEN p_recordset FOR
    select 
        d.dateInRange as dateval,
        p_event as eventdesc,
        nvl(td.dist_ucnt, 0) as dist_ucnt
    from (
        select 
            p_begin_date + rownum - 1 as dateInRange
        from all_objects
        where rownum <= p_end_date - p_begin_date + 1
    ) d
    left join (
        select 
            date,
            count(distinct usersid) as dist_ucnt
        from
            txn_dec
        where eventDesc = p_event
        group by date 
    ) td on td.date = d.dateInRange;
END getDateRange;