[xquery-talk] where clause

G. Ken Holman gkholman at CraneSoftwrights.com
Wed Mar 27 05:18:41 PST 2013

At 2013-03-27 08:31 -0400, Michael Sokolov wrote:
>I'm trying to come up with examples in which "where" clauses cannot 
>be rewritten as XPath predicates.  So far, the ones I have all 
>involve an "at" counter.  Are there others?

I can see no difference off hand when creating 1-tuples, as a 1-tuple 
is essentially just a sequence.

However, when creating n-tuples (either with the "at" keyword as you 
say or with other bound variables in your expression), the where 
clause acts on the tuple, not just on a set of values.  Here is a 
3-tuple expression example:

    for $a in expr1, $b in expr2, $c in expr3
    where $a=$b+$c
    return $a

I hope this is helpful.

. . . . . . . . Ken

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