Built-in functions

Db2 XQuery provides a library of built-in functions for working with XML data. These built-in functions include XQuery-defined functions and Db2 built-in functions.

XQuery-defined functions: XQuery-defined functions are in the namespace that is bound to the prefix fn. This namespace is the default function namespace, which means that you can invoke XQuery-defined functions without specifying a namespace prefix. If you override this default function namespace with a default function namespace declaration in the query prolog, you must use the prefix fn to invoke XQuery-defined functions.
Db2-defined functions: The Db2-defined functions are db2-fn:xmlcolumn and db2-fn:sqlquery, which you use to access XML values from a Db2 database. The prefix db2-fn is not the default function namespace, so you must use the namespace prefix when invoking these functions unless you override the default namespace with a default function namespace declaration in the query prolog.