Question

I would like to generate the following sql from ICriteria

select   c.Id, 
       sum(c.Amount) Amount,
       (select COALESCE(max(AuditDate), c.WhenAdded) FROM Audit a WHERE c.Id = a.CId) StatusDate
from    c
join    l
on  c.Id = l.CId
Group By c.Id, c.WhenAdded

So far i have

ICriteria crit = CurrentSession.CreateCriteria<C>()
     .CreateAlias("L", "l")
     .SetProjection(Projections.ProjectionList()
     .Add(Projections.Group<C>(x => x.Id), "Id")
     .Add(Projections.Sum("l.Amount"), "Amount")
     .Add(Projections.SubQuery(DetachedCriteria.For<Audit>("ca")
        .SetProjection(Projections.ProjectionList().Add(
              Projections.SqlFunction("COALESCE", 
                NHibernateUtil.DateTime, 
                Projections.Max<ClaimAudit>(x=> x.AuditDate),
                Projections.Property<C>(x => x.WhenAdded)), "StatusDate"))))
     .SetResultTransformer(Transformers.AliasToBean<CDto>());

BUT I cannot get the parent column in the coalesce of the child subquery. I get the following exception

Could not find property C.WhenAdded

I know that the sub query is looking for a column called WhenAdded in the child query but not sure how to tell it to look in the parent?
Any ideas on how to acheive this?

ps. I need to do this in this converluted way otherwise i get an incorrect sum on amount. so no suggestions to re write without a subquery unless this is taken in to account.

Thanks.

Answer 1

move the coalesce out from the subquery and use an alias to restrict the Adit entries

ICriteria crit = CurrentSession.CreateCriteria<C>("c")
     .CreateAlias("L", "l")
     .SetProjection(Projections.ProjectionList()
         .Add(Projections.Group<C>(x => x.Id), "Id")
         .Add(Projections.Group<C>(x => x.WhenAdded), "WhenAdded")
         .Add(Projections.Sum("l.Amount"), "Amount")
         .Add(Projections.SqlFunction("COALESCE", NHibernateUtil.DateTime, 
             Projections.SubQuery(DetachedCriteria.For<Audit>()
                 .Add(Restrictions.PropertyEq("C.Id", "c.Id")
                 .SetProjection(Projections.Max<ClaimAudit>(x=> x.AuditDate)),
             Projections.Property<C>(x => x.WhenAdded)), "StatusDate")))
     // AliasToBean !?
     .List();