Get an entry, and if not, then the parent element?

Question

SQL

Faced a problem, in sql I am weak.
there is such a structure:
page - id, title, parent_id
options - id, name
page_options - id, option_id, page_id, value should
work like this:
for the current id is not found, then we look at the parent of the current page and return the options for the parent.
How to implement something like this, without unnecessary checks in php and unnecessary requests, how would it be right?
Here is such a scheme: