Hi Cerstin,


However, I am not sure if it is possible at all to mix displaying 
(in the "then" part) and updating (in the "else" part)

True - that's actually a limitation of the update specification, wich forbids
mixing updating and non-updating expressions. You can find some information
on it in our documentation [1] and in the actual XQuery specification [2].
As a consequence you have to insert the new query element during a
consecutive query.
 

If it is possible, I guess I have to include the name of the collection for insertion 
by using db:open? Is it necessary to specify the exact place for insertion (as in 
my example) as this should be already determined by the condition?

Declaring a variable via the Let expression would help to specify the exact
location only once ... but of course as you have to insert the node during
a second query it's not helping here.

Sorry that I can't provide you with a better solution ... feel free to ask for more.


Best regards,
Lukas

[1] http://docs.basex.org/wiki/Update#Returning_Results
[2] http://www.w3.org/TR/xquery-update-10/#id-conditional-expr