Chapter 9. User-Defined Functions and Triggers

In this chapter, you will learn

• What User-Defined Functions (UDFs) are

• How UDFs can be used to simplify your application development efforts

• What triggers are

• How triggers can be used to transparently and consistently enforce application logic in the database

UDFs and triggers are database objects that help reduce the complexity of database application development.

On LUW, although the language syntax for SQL PL is consistent for all types of objects from an application development perspective, the language implementation to support SQL PL for stored procedures is different from that for UDFs and triggers. SQL PL support in UDFs and triggers is a subset of that in stored procedures. It is referred to as the inline SQL PL.

Note

Although the UDFs and triggers are covered in this chapter, inline SQL PL is not discussed here. Appendix B, "Inline SQL PL for DB2 UDB for Linux, UNIX, and Windows," is fully dedicated to the topic and introduces how to implement stand-alone code as well.

On iSeries and zSeries, SQL UDFs and triggers are implemented just like SQL procedures. They are compiled during the creation process and the corresponding programs are executed when the objects are invoked.