nhibernate criteria for selecting from different tables

Question

I have following table model:

I want following SQL command as nhibernate c

Answer 1

If you want the last five orders I would approach the problem with a slightly different query

Select * 
From order o join Units U on O.OID = U.OID
Order by O.PONumber limit 5

in nhibernate would be something like that (not tested)

Order orderAlias = null;
Unit unitAlias = null;
var query = session.QueryOver(() => orderAlias)
   .JoinAlias(() => orderAlias.Units, () => unitAlias, JoinType.InnerJoin)
   //.TransformUsing(Transformers.DistinctRootEntity) if you have duplicates
   .OrderBy(x => x.PONumber).Desc.Take(5);

UPDATE

You could also just load Order entity. NHibernate will load automatically all units rows, based on your mapping info (lazy/eager loading or joins).

var query = session.QueryOver().OrderBy(x => x.PONumber).Desc.Take(5);