expr Single and expr should evaluate to a node set.
If expr Single contains more than one element node, the modification will be applied to each of the nodes.
BDB XML allows you to modify documents already stored in its containers using XQuery Update statements.
This section provides a brief introduction to update statements so as to help you get going with them.
For example if our original working document is: XQuery Update expressions that add content to a document must first select the location in the document where the content is to be added, and then it must identify where the content is to be added relative to the selected location.
You do this by specifying the appropriate keywords to the update expression.
We thus provide an extension to XQuery, which maps each of the XUpdate instructions to a corresponding XQuery expression.
Until the W3C working group starts its work on an official update specification, the basic syntax follows the proposal by Patrick Lehti. However, it is not suitable for updating temporary document fragments constructed within the XQuery, i.e.
The selection expression that you provide must be a non-updating expression, and the result must be a sequence of zero or more nodes.You can also perform a node update by declaring an update function.XQuery Update does not perform updates (node insertion, deletion, and so forth) until after the query has completed. First, you cannot perform an update and return the results in the same query.An update statement may occur at any position within the XQuery main code or a function body.When using an update within the return clause of a FLWOR expression, it should be clear that one should not delete or replace nodes that are still being used by enclosing code.