Query for nodes based on presence of descendant nodes

[Craig S. Dickson]

Hi,

I would like to query for nodes based on the presence of a descendant node. In 
psuedo code, something like:

select * from nt:base where hasDescendant('./relative/path/to/descendant/node')

I am trying to create the query with SQL2 and I can see the ischild() and 
isdescendant() constraints, but I am not clear how to use them to query for and 
return the parent/ancestor nodes, instead of the child/descendant nodes.

Is this possible? I would prefer and SQL2 answer, but can use QOM or XPath if 
necessary.

Thanks in advance.

Craig