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8 bytes added ,  14:31, 8 December 2010
The most important thing to keep in mind when using XQuery Update is the Pending Update List (PUL). In contrast to other programming languages, XQUF statements are not executed immediately, but are first collected within a set-like structure, the PUL. At the end of a query, all update primitives on this list are applied after being checked for compatibility. If a conflict exists, an error message is returned and all accessed databases remain untouched (atomicity). For the user this means updates are only visible <b>after</b> the end of a snapshot.
;===Returning Results===:It is not possible to mix different types of expressions in a query result. The outermost expression of a query must either be a collection of updating or non-updating expressions. Generally there is no way to perform any updating queries and return a result at the same time. But a simple and convenient workaround exists. common error: copy/fragment of dbnode-> change for result. better use transform
;===Function Declaration===:To use updating expressions within a function, the 'updating' flag has to be added to the function declaration. A correct declaration of a function that contains updating expressions (or a function that calls updating functions) looks like this: declare <b>updating</b> function { ... }
==New Functionality==
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