一个使用EF进行查改的样例

 数据库管理软件是MS SQL，数据库是微软的NorthWind。

主体代码,完整的解决方案见最下方

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestCodeFirst
{
    class Program
    {
        static void Main(string[] args)
        {
            ValidaProduct();
            UpdateProduct();
            GetSpecialProduct();
        }

        private static void ValidaProduct()
        {
            using (Northwind northwind = new Northwind())
            {
                var product = northwind.Products.Find(1);
                Console.WriteLine(string.Format("product.Name{0} product.UnitPrice:{1}", product.ProductName, product.UnitPrice));
                product.ProductName = null;
                product.UnitPrice = 2.33M;
                product.Discontinued = false;
                northwind.SaveChanges();
            }
        }

        private static void UpdateProduct()
        {
            using (Northwind northwind = new Northwind())
            {
                var product = northwind.Products.Find(1);
                Console.WriteLine(string.Format("product.Name{0} product.UnitPrice:{1}",product.ProductName, product.UnitPrice));
                product.UnitPrice = 2.33M;
                product.Discontinued = false;
                northwind.SaveChanges();

                var product2 = northwind.Products.Find(1);
                Console.WriteLine(string.Format("product.Name{0} product.UnitPrice:{1}", product.ProductName, product2.UnitPrice));
            }
        }

        private static void GetSpecialProduct()
        {
            using (Northwind northwind = new Northwind())
            {
                var product = from p in northwind.Products
                              where p.Category.CategoryName == "Beverages"
                              select p;
                foreach (var item in product)
                {
                    Console.WriteLine(string.Format("ProductName:{0}", item.ProductName));
                }
                Console.WriteLine(string.Format("执行结果：{0}", product == null));
            }
        }
    }
}

完整下载