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embed yourself in db2
on December 26, 2004
The book describes IBM's Procedural Language, which runs on their db2 servers. It is not a general purpose language, like C or Java. Rather, it is tied directly to db2 and IBM's implementation of SQL. But within this context, the book explains the expressive power of PL. It shows at length how you can write stored procedures, triggers and functions in PL. The level of detail and the cited examples should reassure you of PL's capability.
But why even write business logic code at the database layer? There have been other books on n-tier application design, which call for the locating of business logic in a middle tier and not at the database. The authors' rejoinder is that while that makes for an elegant design, practical experience shows that often, crucial logic needs to be at the database. This reduces networks traffic and can heavily improve perforance. Hence the need for PL, or something like it.
Be wary of the book's claim that PL lets you write "portable application logic". It is portable only between instances of db2 running under linux, unix, Microsoft Windows or IBM's operating systems. When you write embedded logic in PL, you are also embedding yourself or your company into db2. Which may indeed be fine by you. But just so you know.