Expression evaluation and processing

A number of operations are often included in the processing of expressions. These operations include extracting atomic values from nodes, using type promotion and subtype substitution to obtain values of an expected type, and computing the Boolean value of a sequence.

In DB2® XQuery, updating expressions can be used only within the modify clause of a transform expression. For information about the XQuery transform expression, and updating expression processing, see Transform expression and Use of updating expressions in a transform expression.