link如何更新DataTable，如下代码怎么用？

NorthwindEntities db = new NorthwindEntities();

Customer cust = (from c in db.Customers

             where c.CustomerID == "LAWN"

             select c).Single();

cust.ContactName = "John Smith";

cust.Fax = "(800) 123 1234";

db.SaveChanges();