Dear Shuxin, > Both Saxon and BaseX return the result node set [1, 2]. However, the nodes > with id 2 and 3 seems identical to me and is hard to understand why node 2 is > selected while 3 is not. If node 2 is deleted from the XML document, result > set [1,3] is returned. I'm interested in whether this is intended behavior > which I might have limited knowledge of? If it is also of interest for you > you may have a look. Thank you very much!
The semantics here are tricky: • boolean(.) gives you true() or false() • true() is returned for all 3 elements • xs:double(true()) returns 1, so your query is equivalent to //*[1] • ...[1] returns the first item of the input • //* returns the 3 elements P1, A1 (id="2") and A1 (id="3") • //* is a shortcut for /descendant-or-self::node()/child::* • /descendant-or-self::node() returns 7 results (1 document, 3 elements, 3 texts) • the document has 1 P1 child node; P1 has 2 A1 child nodes • //*[1] returns a) the P1 child node and b) the first A1 child node …and Martin was faster with his response, as I just see ;) If you want to get only the first result of all results, you can use parentheses: (//*[.....])[1] Hope this helps, Christian
