I have a complicated query which I'm building using Criteria/Restrictions etc

The Hibernate object hierarchy is like...

An expert has expertise in one of more tools (a set property at the Expert level), and the ToolExpertise has two class instance properties: 'Tool' (i.e. Excel, Eclipse), and 'Competence' (beginner/average/expert). For example: 'Fred' is an expert who has two ToolExpertise instances: Eclipse/Average and Excel/Expert.

The query is designed to return a list of all experts that match the declared tool/competence parameters, one which there can be one or more pairs.

I use the Criteria methods to map a sub criteria to the ToolExpertise set and alias mappings from that to Tool and Competence. I then use the alias names to build the Restrictions.

I have a problem in trying to search for multiple Tool/Competence pairs. For instance, if I search for...
Eclipse/Average OR Excel/Expert
.... then it brings back the right set of Experts. However if I search for...
Eclipse/Average AND Excel/Expert
... then I get nothing back, even though I know there is one matching test record that exists.

I suppose in a way this boils down to a logical table like..

Hence, from the example table above I want to search for any expert that is linked to both Tool value '1' and '2', i.e. expert 'A'

Any ideas?

I've worked out how to build a SQL version of the required query, like...

Any suggestions for how I translate this into 'Projections' based extension to my Criteria based query?