On 11/14/17, 1:42 AM, "basex-talk-bounces@mailman.uni-konstanz.de on behalf of Christian Grün" <basex-talk-bounces@mailman.uni-konstanz.de on behalf of christian.gruen@gmail.com> wrote: > How can database updating be done inside map:for-each ? The higher-order functions of the XQuery spec are currently restricted to non-updating functions. You can circumvent this restriction by enabling the MIXUPDATES option, or using traditional iterations (which are, at least, not much slower than map:for-each): for $key in map:keys($map) let $val := $map($key) return (...) I will offer that if the question is being asked because it matches what would be done in other languages, it’s probably a good idea to read about functional programming, which XQuery is associated with. A purely functional program would not directly cause side-effects within a function. At least, some familiarity with functional programming is fundamentally important in learning about XQuery. Kendall