the docs I read said that the recommended method (prior to the last release) was to write a C program to do it. My understanding is that you write your trigger code outside the database, compile it and then link it to the trigger mechanism of the database. The docs say that you can write it in SQL, but if you do, you need a C compiler on the host (presumeably to convert your SQL to C).

I've only got tangental experience with it, but it looks like here's what happened:
1. IBM makes an AS/400 with a proprietary database with RPG/COBOL in mind.
2. IBM decides to rename this old database DB2/400 (not the "real" DB2 at all).
3. IBM SLOWLY adds Sql functionality to DB2/400.

Just read a document from IBM on converting your MS Sql Server and/or Sybase Sql Server applications to DB2/400. It has a short description of the differences in architecture and says that a primary difference is that DB2/400 is an ISAM database that has had some Sql functionality added, with more additions planned.

Personally, I've seen enough. From what I've read, the other DB2 is a pretty good product. But why anyone would want to run DB2/400 is well beyond my comprehensive abilities.