public List<News> GetCustomersWithOrders()
        {
            List<News> p = (from n in objDataContext.News
                    where n.CID == n.NewsCatalog.CatalogID
                    select new {类别=n.NewsCatalog.CatalogName,标题=n.NewsTitle,日期=n.NewsDate }).ToList();
            return p;
        }

public List<News> GetCustomersWithOrders()
        {
            List<News> p = (from n in objDataContext.News
                            from c in objDataContext.Catalog
                    where n.CID == c.CatalogID
                    select new News(){类别=n.NewsCatalog.CatalogName,标题=n.NewsTitle,日期=n.NewsDate }).ToList();
            return p;
        }

------解决方案--------------------
LINQ使用JOIN  
var q =  
from e in db.Employees  
join o in db.Books on e.EmployeeID equals o.EmployeeID into b  
from x in b.DefaultIfEmpty()  
select new  
{  
e.ID,  
e.Name,  
o.BookName  
};

------解决方案--------------------

探讨

我知道这个最后返回的是object类型，在三层中如何去返回呢，总不能是object类型吧