A database system and method allows a user to write program code in a high-level programming language that implements a class that defines the structure of a user-defined type and methods that can be invoked on instances of the type. The class is then registered with the database system, which enforces...http://www.google.com.hk/patents/US20050177583?utm_source=gb-gplus-share專利 US20050177583 - System and method for providing user defined types in a database system
