XQuery 3.1 is a versatile query and application development language, capable of processing the information content of diverse data sources including structured and semi-structured documents, relational databases and tree-bases databases. The XQuery language is designed to support powerful optimizations and pre-compilation leading to very efficient searches over large amounts of data, including over so-called XML-native databases that read and write XML but have an efficient internal storage.

XQuery 3.0 (renamed from XQuery 1.1 to align with the family of "3.0" specifications) is a versatile markup language, capable of labeling the information content of diverse data sources including structured and semi-structured documents, relational databases, and object repositories. Important new features since XQuery 1.0 include:

• The "group by" clause, windowing ("tumbling window" and "sliding window"), the "count" clause, and the "allowing empty" clause in FLWOR expressions
• A try/catch capability to support application handling of errors
• Literal function items, inline functions, dynamic function invocations, and function item coercion
• Nondeterministic functions and private functions
• A value-based switch expression (analogous to the existing typeswitch expression)
• Computed namespace constructors
• Declaration of serialization parameters
• Support for new Functions and Operators 3.0 capabilities
• Cleaner definition of module import

XQuery 1.1 fixes some bugs and adds some substantial new features to XQuery 1.0.