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Re: Empty sequences in "for" clause bindings

From: Jerome Simeon <simeon@us.ibm.com>
Date: Thu, 8 Jul 2004 13:43:17 -0400
To: Stéphane Mbaye <stephane.mbaye@gael.fr>
Cc: "XQuery" <www-ql@w3.org>
Message-ID: <OFE4951F94.FBDF051B-ON85256ECB.0060F69E-04256ECB.006158FF@us.ibm.com>
Stephane,

The result of your query is the empty sequence.

Variables in for expressions always bind to each items in the
input sequence. Since the input sequence here is empty, the $a variable is
never bound to anything (it is *not* bound to the empty sequence)
and the outermost for expression never executes the left-hand side
sub-expression.

Best,
- Jerome




Stéphane Mbaye <stephane.mbaye@gael.fr> 
Sent by: www-ql-request@w3.org
07/08/2004 12:58 PM

To
"XQuery" <www-ql@w3.org>
cc

Subject
Empty sequences in "for" clause bindings






Dear all,
 
how “for” clause tuples are generated when some of the bounded variables 
match the empty sequence ?
 
For example should the following query return (1, 2, 3), an error or 
anything else ?
 
for $a in (), $b in (1, 2, 3)
return ($a, $b)
 
 
Regards
 

 
Stéphane
Mbaye

 
GAEL Consultant 
Cité Descartes
18, rue Albert Einstein
77420 Champs-sur-Marne
France 
Software Director
 
mailto:stephane.mbaye@gael.fr
http://www.gael.fr 
 
 
tel +33-(0)1 64 73 99 55
fax +33-(0)1 64 73 51 60
 
 
 
 

Received on Thursday, 8 July 2004 13:44:15 UTC

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