Java Persistence with Hibernate

8.2. Customizing SQL

SQL started its life in the 1970s but wasn't (ANSI) standardized until 1986. Although each update of the SQL standard has seen new (and many controversial) features, every DBMS product that supports SQL does so in its own unique way. The burden of portability is again on the database application developers. This is where Hibernate helps: Its built-in query mechanisms, HQL and the Criteria API, produce SQL that depends on the configured database dialect. All other automatically generated SQL (for example, when a collection has to be retrieved on demand) is also produced with the help of dialects. With a simple switch of the dialect, you can run your application on a different DBMS.

To support this portability, Hibernate has ...