Drools 5.2 allows queries to call queries. It also allows rules to call
a query. It also allows "unification" of variables, which means a
variable can be left unbound.
That said quite a few bugs have turned up and I strongly recommend you
use HEAD for the moment on this feature:
https://hudson.jboss.org/jenkins/job/drools/lastSuccessfulBuild/artifact/...
Look at the "New and Noteworthy" docs on the backward chaining
derivation queries. ch05 might need to be updated with better clarification.
Mark
On 14/07/2011 15:27, Simon Chen wrote:
Hi all,
I am wondering if it is possible to write more complex queries, e.g.,
running a query inside of a query. An example is that I have one query
to enumerate all books, and have another query to enumerate the people
that have not read all books.
According to a colleague of mine, the syntax for a query only allows
the entity LHS in its declaration:
http://docs.jboss.org/drools/release/5.2.0.CR1/drools-expert-docs/html/ch...
By definition, the entity LHS cannot contain the keyword query, as it
can only contain conditional elements:
http://docs.jboss.org/drools/release/5.2.0.CR1/drools-expert-docs/html/ch...
Any thoughts?
Thanks.
-Simon
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