Linq to sql 增删改查

配置文件 

<connectionStrings>
  <add name="NorthwindConnectionString" connectionString="Data Source=.;Initial Catalog=Northwind;Integrated Security=True" providerName="System.Data.SqlClient"/>
 </connectionStrings>

代码：

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace LINQPart1
{
    public partial class _Default : System.Web.UI.Page
    {
      
        protected void Page_Load(object sender, EventArgs e)
        {
            ShowProducts();
        }

      

        protected void Select_Click(object sender, EventArgs e)
        {
            ShowProducts();

        }

        private void ShowProducts()
        {
            NorthwindDataContext db = new NorthwindDataContext();

            var products = from p in db.Products
                           where p.Category.CategoryName == "Beverages"
                           orderby p.ProductID descending
                           select new { p.ProductID, p.ProductName, p.Category.CategoryName, Price = p.UnitPrice };

            GridView1.DataSource = products;
            GridView1.DataBind();
        }

        protected void Insert_Click(object sender, EventArgs e)
        {
            NorthwindDataContext db = new NorthwindDataContext();

            Product p1 = new Product { CategoryID = 1, ProductName = "Scott's Apple Juice", UnitPrice = 4.23m };
            db.Products.InsertOnSubmit(p1);
            db.SubmitChanges();
            ShowProducts();
        }

        protected void Update_Click(object sender, EventArgs e)
        {
            NorthwindDataContext db = new NorthwindDataContext();

            Product product = db.Products.First(p => p.ProductName.StartsWith("Scott's"));
            product.UnitPrice += 2.25m;
            db.SubmitChanges();
            ShowProducts();
        }

        protected void Delete_Click(object sender, EventArgs e)
        {
            NorthwindDataContext db = new NorthwindDataContext();
            Product product = db.Products.First(p => p.ProductName.StartsWith("Scott's"));
            //foreach ()
            db.Products.DeleteOnSubmit(product);
            db.SubmitChanges();
            ShowProducts();

        }
    }
}