ASP.NET MVC 3中的LINQ to SQL

Question

What is LINQ for following SQL query for selecting NULL values from ParentCategoryID column:

SELECT ID, CategoryName, ParentCategoryID FROM Category 
WHERE (ParentCategoryID IS NULL)

I have try following LINQ but doesn't work:

from u in db.Categories 
where (u.ParentCategoryID == null) 
select u

Answer 1

make some class, containing fields, those you select (Class1)

List<Class1> list = CategoryRepository.Categories
                        .Where(x => x.ParentCategoryId != null)
                        .Select(x => new Class1(x.CategoryName, x.ParentCategoryId)
                        .ToList();