Chapter 10. Subquery Factoring
You may not be familiar with the term subquery factoring. Prior to the release of Oracle 11gR2, the official Oracle documentation barely mentions it, providing just a brief synopsis of its use, a couple of restrictions, and a single example. If I instead refer to the
WITH clause of the
SELECT statement, you will probably know immediately what I mean as this term is more recognizable. Both terms will be used in this chapter.
With the release of Oracle 11gR2 (version 11.2), the
WITH clause was enhanced with the ability to recurse; that is, the factored subquery is allowed to call itself within some limitation. The value of this may not be readily apparent. If you have used the
CONNECT BY clause to create ...