PostgreSQL provides advanced features that allow you to avoid writing a program to solve common problems when dealing with data structures and SQL statements. Thanks to the RETURNING predicate, it is possible for you to get back automatically generated data, such as an incremental key. Conflict resolution allows us to perform a kind of 'tuple merging' when dealing with INSERT and UPDATE statements against the same tuples, but one of its most powerful features is surely the Common Table Expression, which not only allows us to re-write complex queries by splitting them into more readable pieces, but also allows us to perform statement pipelining and recurse over a result set.
Knowing these features will allow you to interact with a PostgreSQL cluster efficiently and solve common problems in your day-to-day use quickly and easily.
In Chapter 3, The PL/pgSQL Language...