Handle Date conversion error without function

Question

Hi,
Database version 12.1 - though I would also like to hear if the solution is possible for 9i DB too, as I am pulling data from a view over a DB Link, and would prefer to have the date fix within the view to having to recreate the view logic in my datawarehouse.
A small illustrative sample of what I want.
Sample Data
create table descriptors (attribute1 varchar2(25), creation_date date);
insert into table descriptors (attribute1, creation_date) values ('010612',sysdate);
insert into table descriptors (attribute1, creation_date) values ('310612',sysdate);
commit;And the result I am after, in pseudo code....
select case when to_date(attribute1,'DDMMYY') = error then creation_date else to_date(attribute1,'DDMMYY') end as safe_date from descriptorsYes - I know this will not work!!
And yes, I know storing dates as text is not best practise, this is drill down data from Oracle e-business feeder files, decisions that were made before I had any influence over them - so I am having to make the best of a bad job.
thanks for your input,
Robert.

Answer 1

Etbin wrote:
select case when case when to_number(substr(attribute1,3,2)) not between 1 and 12
then 'error'
when to_number(substr(attribute1,1,2)) not between 1 and to_number(to_char(last_day(to_date(substr(attribute1,3),'mmrr')),'dd'))
Neat solution !
I'll remember that.
But I fail to understand why the 2 embedded case ?
Should this be enough ?with
descriptors(attribute1,creation_date) as
(select '010612',trunc(sysdate) from dual union all
select '110612',trunc(sysdate) from dual union all
select '210612',trunc(sysdate) from dual union all
select '310612',trunc(sysdate) from dual
select case when to_number(substr(attribute1,3,2)) not between 1 and 12
                      then creation_date
                      when to_number(substr(attribute1,1,2)) not between 1 and to_number(to_char(last_day(to_date(substr(attribute1,3),'mmrr')),'dd'))
                      then creation_date
            else to_date(attribute1,'ddmmrr')
       end checked
  from descriptors
/