Strings are probably the most used type of atomic values in queries. This chapter discusses constructing and comparing strings and provides an overview of the many built-in functions that manipulate strings. It also explains string- and text-related features such as whitespace handling and internationalization.
The basic string type that is intended to represent generic character data is called, appropriately,
xs:string type is not the default type for untyped values. If a value is selected from an input document with no schema, the value is given the type
xs:string. However, it is easy enough to cast an untyped value to
xs:string. In fact, you can cast a value of any type to
xs:string and cast an
xs:string value to any type.
xs:string type is a primitive type from which a number of other types are derived. All the operations and functions that can be performed on
xs:string values can also be performed on values whose types are restrictions of
xs:string. This includes user-defined types that appear in a schema, as well as built-in derived types such as
xs:ID. For a complete explanation of the built-in types, see Appendix B.
There are three common ways to construct strings: using string literals, the
xs:string constructor, and the
Strings can be included in queries as literals, using double or single quotes. For example, ...