XQuery reference

Db2® provides support for the XQuery language.

Db2 XQuery concepts
The following topics introduce basic XQuery concepts and describe how XQuery works with a Db2 database.
Type system
XQuery is a strongly-typed language in which the operands of various expressions, operators, and functions must conform to expected types. The type system for Db2 XQuery includes the built-in types of XML Schema and the predefined types of XQuery.
Prolog
The prolog is series of declarations that define the processing environment for a query. Each declaration in the prolog is followed by a semicolon (;). The prolog is an optional part of the query; a valid query can consist of a query body with no prolog.
Expressions
Expressions are the basic building blocks of a query. Expressions can be used alone or in combination with other expressions to form complex queries. Db2 XQuery supports several kinds of expressions for working with XML data.
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.
Regular expressions
A regular expression is a sequence of characters that act as a pattern for matching and manipulating strings.
Limits
Db2 XQuery has size limits and limits for data types.