[tmql-wg] Negation in the different TMQL candidates
Wed, 31 Mar 2004 20:49:11 -0500
On Mar 31, 2004, at 9:24 AM, Rani Pinchuk wrote:
>> TMPath has default "existence" quantification in "=" and "!="
>> operators. Both operators are applied to sequences which are already
>> "generated" by TMPath expressions.
>> "!=" is true if there is at least one element in left sequence and at
>> least one in right sequence which are not equal
>> TMPath has also explicit "every $X in ... satisfies ..." and "some $X
>> in .... satisfies ..." expressions.
>> In some cases FLOR expressions are used to provide equivalent of SQL
>> left joins
> Hi Dmitry,
> I am not sure I understand from the above how your query works:
> for $Person in
> return $Person/bn::*
> I read it as follows:
> For each $Person which is of type 'person', and does not play the role
> 'author' in an association of type 'is-author-of'...
> But where it states that it doesn't play in ANY association of that
> in that role? Or this is the default behavior in TMPath?
That's default behavior. TMPath favors existential queries
> I suspect that the following query might be useful for me to understand
> how TMPath does things:
> How can you show all the topics that play in an association with the
> association type next to it? In Toma it is:
> select $player, $association where $association->$role = $player;
Using FLOR expression:
for $A in /a[*]
for $Player in $A/roleof::*