XQuery

Sequence Types and Schemas

Chapter 11 showed how sequence types are used to match sequences in various expressions, including function calls. When schemas have been imported into a query, additional tests are available for sequence types, including testing for name and type. Their syntax is shown in Figure 13-4. These tests can be used not just in sequence types but also as kind tests in path expressions.

Figure 13-4. Element and attribute tests (for sequence types and kind tests)

Chapter 11 introduced the element( ) and attribute( ) tests. For example, you can use the test element(prod:product) to test for elements whose name is prod:product.

These tests can also be used with user-defined types. For example, the sequence type:

element(prod:product, prod:ProductType)

matches an element whose name is prod:product and that has the type prod:ProductType, or any type derived by restriction or extension from prod:ProductType. Yet another syntax is:

element(*, prod:ProductType)

which matches any element that has the type prod:productType (or a derived type), regardless of name. Note that the element must already have been validated and annotated with the type prod:ProductType. It is not enough that it would be a valid instance of that type if it were validated.

You can also match an element or attribute based on its name using the schema-element( ) and schema-attribute( ) tests. For ...