This is the starting situation:
If END_DATE is NOT NULL, then the previous empty records (= records with NO START_DATE and NO END_DATE) have to be filled with the START_DATE referred to that END_DATE. The final situation has to be the following:
How can I achieve this with a simple SELECT statement, using Oracle analytical functions?
Thank you very much for considering my request.
With sample data you posted (didn't feel like typing everything):
first_value
analytic function might help: