How to convert 2011 -Q4 to 12-31-2011 in oracle sql?

How to convert 2011 -Q4 to 12-31-2011 in Oracle sql?

Answer

This expression should work to transform the value into the date:

select add_months(to_date(substr(yq, 1, 4)||'-01-01', 'YYYY-MM-DD'), substr(yq, -1, 1) * 3) - interval '1' day
from (select '2011-Q4' as yq from dual) x

If you want the date as a particular string format, then use to_char().