ORA-XQ-229-C: Using concatenation to define the result of the FLWOR expr is vague

SECTION 3.8.3: Order by and Return Clauses

In 3.8.3,  the Xquery spec says "The return clause of a
FLWOR expression is evaluated once for each tuple in the 
tuple stream, and the results of these evaluations are
concatenated to form the result of the FLWOR expression".

The usage of the word 'concatenated' is vague here. Since the XQuery
result does not support nested sequences, if a tuple contains
a sequence, all the items of the sequence become the items of the
sequence for the return clause of the FLWOR expression. So in this
sense, the 'concatenation' here really means "Constructing Sequences"
as defined in "3.3.1".  We should define this concatenation process  to be the same as the construction of Sequences specified in 3.3.1.
This also implies that the empty sequence in the tuple is dropped as defined in constuction of Sequences. 'concatenation' does not clarify whether the empty sequence is dropped.

- Steve B.

Received on Monday, 16 February 2004 17:01:21 UTC