Using variable date in a VIEW

Question

Can I create a view in Oracle whereby the date I use to select the records can be a variable?
For example:
select * from marketer_account
where '30-NOV-2009' between mka_eff_dt and mka_exp_dt
and mka_service_type = 'E';
I want to get a list of all records on the marketer account table that were active on 30-NOV-2009.
But more importantly the users want a view that they can run every month to get this information, so in another month we may need the same query but:
select * from marketer_account
where '31-DEC-2009' between mka_eff_dt and mka_exp_dt
and mka_service_type = 'E';
So I want to replace the '31-DEC-2009' with a generic date. I tried this:
select *
from marketer_account
where last_day(add_months(sysdate,-2)) between mka_eff_dt and mka_exp_dt
and mka_service_type = 'E';
This will take the last day of 2 months ago from current: ie. If they run it now, they will get 31-JAN-2010 here.
Is this OK to do? Or is there a better way? Maybe the users want to change the date and run it for a date of their choosing?

Answer 1

Hi,
Besides SYS_CONTEXT, you can also store the base date in a table. If you make it a Global Temporary Table, then different sessions can use different parameters at the same time. You can even have multiple copies of the the same view in the same query, all with different parameters.
If the variable date is always the same distance from today's date, then you can simply use SYSDATE in the view.
For example, to find what was active on the last day of the month 3 months ago:
select  *
from  marketer_account
where   ADD_MONTHS (TRUNC (SYSDATE, 'MONTH'), -2) -1
        between mka_eff_dt
        and     mka_exp_dt
and     mka_service_type = 'E';If you run this any time in March, 2010, it gets the same results as:
select  *
from  marketer_account
where   TO_DATE ('31-Dec-2009', 'DD-Mon-YYYY')
        between mka_eff_dt
        and     mka_exp_dt
and     mka_service_type = 'E';but in April, it's as if the magic date was automatically changed to '31-Jan-2010'.