Extracting a count of distinct values between two date ranges over months

Question

Hi All,
I am having a bit of difficulty in figuring out the query to build a list of active campaigns over a date range.
i.e. I have a table with campaign IDs and their start and end date details like this
Campaign_id     Start_date     End_date
        10001     1-Jun-09     31-May-11
        10002     1-Jun-09     23-Jun-11
        30041     21-Aug-09     31-Dec-09
        20005     3-Jun-10     31-May-11
        90021     21-Nov-09     30-Nov-10
        54000     1-Jun-11     1-Dec-12
        35600     1-Mar-10     31-Mar-12 What the above data means is, for eg. the campaign 10001 is active from 1-Jun-09 to 31-May-11 i.e. for 24 months (inclusive of the month Jun-09 and May-11)
What I need to figure out is the counts of active campaigns between a date range and display that active count at a month level (for e.g. lets say we want to see all the campaigns that were active
between the date range '01-JUN-2007' and '30-APR-2012' ). So the partial output would be as seen below. The list would continue till december-2012
Month    Year    Count of active campaigns
Jan    2009    0
Feb    2009    0
Mar    2009    0
Apr    2009    0
May    2009    0
Jun    2009    2
Jul    2009    2
Aug    2009    3
Sep    2009    3
Oct    2009    3
Nov    2009    4
Dec    2009    4
Jan    2010    3
Feb    2010    3
Mar    2010    4
Apr    2010    4
Dec    2012    1 Could anybody please help me with the right query for this.
Thanks a lot for help
Regards
Goldi

Answer 1

set pagesize 40
with tab as
                select 1 id, sysdate -100 start_date, sysdate end_date from dual
                union
                select 1 id, sysdate -200 start_date, sysdate -150 end_date from dual
                union
                select 1 id, sysdate -600 start_date, sysdate - 400 end_date from dual
                union
                select 1 id, sysdate -300 start_date, sysdate - 150 end_date from dual
                union
                select 2 id, sysdate -100 start_date, sysdate-50 end_date from dual
      year_tab as
                    select
                             add_months(min_date, level -1) m
                    from
                            select min(trunc(start_date,'YYYY')) min_date, add_months(max(trunc(end_date,'YYYY')), 12) max_date
                            from tab
                    connect by level <= months_between(max_date, min_date)
select to_char(m,'YYYY') year_,
         to_char(m,'Month') month_,
         nvl(act, 0) act
from   year_tab,
            select m date_,count(*)  act
            from tab, year_tab
            where m between trunc(start_date,'MM') and trunc(end_date,'MM')
            group by m
            ) month_tab
where m = date_(+)
order by m;
YEAR_ MONTH_           ACT
2010  January            0
2010  February           0
2010  March              0
2010  April              0
2010  May                0
2010  June               0
2010  July               0
2010  August             0
2010  September          1
2010  October            1
2010  November           1
2010  December           1
2011  January            1
2011  February           1
2011  March              1
2011  April              0
2011  May                0
2011  June               0
2011  July               1
2011  August             1
2011  September          1
2011  October            2
2011  November           2
2011  December           2
2012  January            2
2012  February           2
2012  March              2
2012  April              1
2012  May                1
2012  June               0
2012  July               0
2012  August             0
2012  September          0
2012  October            0
2012  November           0
2012  December           0
36 rows selected.