XQuery Reference
Reference 为 XQuery, functional 查询 language 为 XML 数据源.
FLWOR Expressions
XQuery FLWOR expressions (For, Let, Where, Order by, Return) structure queries similar to SQL. The for clause iterates over sequences, let binds variables, where filters, order by sorts, and return constructs output. Expressions can be nested and composed for complex transformations. XQuery can construct new XML nodes, enabling transformation pipelines. The language is Turing-complete and typed.
- for
- Iterate over sequence
- where
- Filter condition
- return
- Construct output
for $b in //bookwhere $b/price > 30return $b/titleFunctions and Types
XQuery has a rich built-in function library including string, numeric, date, and node functions. User-defined functions can be declared with typed parameters and return types. The type system includes atomic types, sequences, and schema-validated nodes. XQuery Update Facility adds insert, delete, and replace operations. Full-text search extensions provide text ranking and stemming.
- built-in
- String, numeric, date funcs
- user functions
- declare function
- update
- Insert/delete/replace
fn: namespacetyped paramsXQuery Update Facility