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.
The built-in types of XML Schema are in the namespace http://www.w3.org/2001/XMLSchema
, which has the predeclared namespace prefix
xs
. Some examples of built-in schema types include xs:integer, xs:string, and
xs:date.
The predefined types of XQuery are in the namespace http://www.w3.org/2005/xpath-datatypes
, which has the predeclared namespace prefix
xdt
. Some examples of predefined types of XQuery include xdt:untypedAtomic,
xdt:yearMonthDuration, and xdt:dayTimeDuration.
Each data type has a lexical form, which is a string that can be cast into the given type or that can be used to represent a value of the given type after serialization.