如何使用NHibernate离开联接两个不同的表

Question

I have three tables (Table A, B and C). I would like to do the following: Left Join A with B and Left join A with C.

Now I have used CreateCriteria, to do the joins using jointype which worked upto a certain point but it's throwing Query exception. It seems this is because it's seems to attempt to left join B with C rather than A and C.

Code:

currencies = session.CreateCriteria(typeof(Currency), "TableA")                 
            .CreateCriteria("FXRates", "TableB",
                            JoinType.LeftOuterJoin, 
                            Expression.Eq("fxrate.RateDate",date))
            .CreateCriteria("FundingRates", "TableC", 
                            JoinType.LeftOuterJoin,
                            Expression.Eq("fundingrate.RateDate", date))
            .Add(Restrictions.IsNotNull("currency.code"))
            .List<Currency>();

Apologies in advanced if I have missed out anything or not provided enough detail, let me know if you need more...

Answer 1

You can use NHibernate "QueryOver" to do it:

session.QueryOver<Item_A>()
   .Left.JoinQueryOver(item_A => item_A.Item_B)
   .Left.JoinQueryOver(item_A => item_A.Item_C)
   .TransformUsing(Transformers.DistinctRootEntity)
   .List();