Implementing Db2 user-defined functions

In contrast to built-in Db2 functions, you can create and implement your own functions to simplify your queries.

There are three primary types of user-defined functions.

Sourced functions

Functions that are based on existing functions.

External functions

Functions that are developed by users.

SQL functions

Functions that are defined to the database by use of SQL statements only.

External user-defined functions can return a single value or a table of values.

• External functions that return a single value are called user-defined scalar functions.
• External functions that return a table are called user-defined table functions.

User-defined functions, like built-in functions or operators, support the manipulation of distinct types.