How do I update two tables at the same time using Linq-to-SQL?

var z = from a in db.Products
                join b in db.ProductSubcategories on 
                     a.ProductSubcategoryID  equals b.ProductSubcategoryID
                join d in db.ProductCategories on 
                     b.ProductCategoryID equals d.ProductCategoryID
                select new { ProductName = a.Name, ProductCategory = d.Name,     
                             ProductSubCategory = b.Name, Cost = a.StandardCost, 
                             discontinuedDate = a.DiscontinuedDate,     
                             ProductId=a.ProductID };