Providing an engine to query the domain model is a primary responsibility of any DAL. If your DAL is then based on an O/RM tool, then providing an API to query the model become s a primary responsibility of the O/RM of choice. For this reason, some O/RM products offer their own variation of the SQL language adapted to work on the domain model. So you have Entity SQL with Entity Framework and the HQL language in NHibernate. More in general each O/RM provides its own specific API for you to arrange a query using criteria, projections, sort expressions as run time conditions and specific use-cases suggest.
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