nhibernate的不支持
linq的不支持：
IQueryable<Model.MessageBoard> iq = new ManagerBase<Model.MessageBoard, Model.MessageBoard>().Query();
IQueryable<Model.Author> iq2 = new ManagerBase<Model.Author, Model.Author>().Query();
IQueryable<Model.Order> iq2 = new ManagerBase<Model.Order, Model.Order>().Query();
IList<Gx.Model.MessageBoard> MessBoard = (from m in iq2
join m2 in iq
on m.AuthorId equals m2.Author.AuthorId into m3
from t in m3
// where m2.AuthorId<15 .............................没编译就直接报错
//where m.AuhtorID<15 .................................没有问题（但是，我想要的是用m2.AuthorId作条件，不知道如何解决。）
select new Gx.Model.MessageBoard { Mb_id = t.Mb_id, FromID = t.FromID, Realname = t.FromID != 0 ? t.Author.RealName : t.Realname, MBIP = t.FromID != 0 ? t.Author.OtherAddress : t.MBIP, MBMessage = t.MBMessage, MBMessageDate = t.MBMessageDate, Author = t.Author })
.Take(Count)
//.where(o=>o.AuthorId) .......................编译后也会报错。
.ToList<Gx.Model.MessageBoard>()
;
MessBoard = MessBoard
.OrderByDescending(o => o.Mb_id)
.ToList();
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from c in Customers
from p in c.Purchases.DefaultIfEmpty()//DefaultIfEmpty()在linq中可以实现左连接，但是在nhibernate to linq中却不行。
select new { c.Name, p.Description, Price = (decimal?)p.Price }
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HQL的不支持：
string HQL = "SELECT t.Mb_id ,t.FromID ,(case when t.FromID!=0 then A.RealName else t.Realname end),(cast(t.MBMessage as string)),t.MBMessageDate,cast(A.Username as string) from Author A right join MessageBoard t on A.AuthorID=t.FromID//当两张表不存在父子关系的时候，不能使用这种方式连表（用linq和sql可以实现）
where A.AuthorId=:AID group by t.Mb_id,t.FromID,A.RealName,t.Realname,t.MBMessage,t.MBMessageDate,A.Username";
