Select records based on monthly anniversary date

Question

Hi,
I have a table with a date_added field and I want to select records based on the monthly anniversary date of this field.
eg. ID, Date_added
1, 10-DEC-2012
2, 11-NOV-2012
3, 10-MAR-2012
4, 28-FEB-2012
5, 30-DEC-2012
So For the 10th of Jan 2013, I would want to return records 1 and 3 only
I started looking at the extract function, but this soon falls down for records at the end of the month. For example, on the 28th Feb, I would also want to include records where the date_added day is the 29th, 30th or 31st. So, in the table above I would want to return records 4 and 5, but extract would only return 4.
Is there a simple function to do this month anniversary query - am I missing something very obvious? Or, do I need to write a query to explicitly cope with dates at the end of the month? So far I haven't found a sensible simple solution!
I'm using 11g
thanks

Answer 1

I didn't look into leap year, but this should give you a starting point:
select  *
  from  t
  where 1 = case last_day(to_date(:target_date,'mmddyyyy'))
              when to_date(:target_date,'mmddyyyy')
                then case
                       when to_char(date_added,'dd') >= to_char(to_date(:target_date,'mmddyyyy'),'dd')
                         then 1
                     end
              else case
                       when to_char(date_added,'dd') = to_char(to_date(:target_date,'mmddyyyy'),'dd')
                         then 1
                     end
            end
/For example, target date is 1/10/2013:
SQL> variable target_date varchar2(8)
SQL> exec :target_date := '01102013';
PL/SQL procedure successfully completed.
SQL> with t as (
  2             select 1 id,to_date('10-DEC-2012','dd-mon-yyyy') date_added from dual union all
  3             select 2,to_date('11-NOV-2012','dd-mon-yyyy') from dual union all
  4             select 3,to_date('10-MAR-2012','dd-mon-yyyy') from dual union all
  5             select 4,to_date('28-FEB-2012','dd-mon-yyyy') from dual union all
  6             select 5,to_date('30-DEC-2012','dd-mon-yyyy') from dual
  7            )
  8  select  *
  9    from  t
10    where 1 = case last_day(to_date(:target_date,'mmddyyyy'))
11                when to_date(:target_date,'mmddyyyy')
12                  then case
13                         when to_char(date_added,'dd') >= to_char(to_date(:target_date,'mmddyyyy'),'dd')
14                           then 1
15                       end
16                else case
17                         when to_char(date_added,'dd') = to_char(to_date(:target_date,'mmddyyyy'),'dd')
18                           then 1
19                       end
20              end
21  /
        ID DATE_ADDE
         1 10-DEC-12
         3 10-MAR-12
SQL> And target date is 2/28/2013:
SQL> exec :target_date := '02282013';
PL/SQL procedure successfully completed.
SQL> with t as (
  2             select 1 id,to_date('10-DEC-2012','dd-mon-yyyy') date_added from dual union all
  3             select 2,to_date('11-NOV-2012','dd-mon-yyyy') from dual union all
  4             select 3,to_date('10-MAR-2012','dd-mon-yyyy') from dual union all
  5             select 4,to_date('28-FEB-2012','dd-mon-yyyy') from dual union all
  6             select 5,to_date('30-DEC-2012','dd-mon-yyyy') from dual
  7            )
  8  select  *
  9    from  t
10    where 1 = case last_day(to_date(:target_date,'mmddyyyy'))
11                when to_date(:target_date,'mmddyyyy')
12                  then case
13                         when to_char(date_added,'dd') >= to_char(to_date(:target_date,'mmddyyyy'),'dd')
14                           then 1
15                       end
16                else case
17                         when to_char(date_added,'dd') = to_char(to_date(:target_date,'mmddyyyy'),'dd')
18                           then 1
19                       end
20              end
21  /
        ID DATE_ADDE
         4 28-FEB-12
         5 30-DEC-12
SQL> SY.