NHibernate Criteria Query - Select Distinct with Joined Entity

问题

I have a Person entity. Every person has a country, I want to select all the distinct countries that have people in them. This Criteria Query returns all the distinct CountryID's

criteria.SetProjection(Projections.Distinct(Projections.Property("Country")));

How do I alter it to join and fetch the Country entity, not just the ID?

回答1:

Any easy way would be to use a subquery. That is, you could select the whole country on the outer query where the country ID matches the inner query.

Subqueries.PropertyIn(
  "Country",
  innerDetachedCriteriaWhichFindsCountriesWithPeopleAndProjectsCountryId)

来源：https://stackoverflow.com/questions/1753161/nhibernate-criteria-query-select-distinct-with-joined-entity