一步一步学Linq to sql（二）：DataContext与实体

public partial class NorthwindDataContext : DataContext

{

    public Table<Customer> Customers;

    public NorthwindDataContext(IDbConnection connection) : base(connection) { }

    public NorthwindDataContext(string connection) : base(connection) { }

}

NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");

GridView1.DataSource = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new { 顾客ID = c.CustomerID, 顾客名 = c.Name, 城市 = c.City };

GridView1.DataBind();

using System.IO;

NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");

StreamWriter sw = new StreamWriter(Server.MapPath("log.txt"), true); // Append

ctx.Log = sw;

GridView1.DataSource = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new { 顾客ID = c.CustomerID, 顾客名 = c.Name, 城市 = c.City };

GridView1.DataBind();

sw.Close();

SELECT [t0].[CustomerID], [t0].[ContactName], [t0].[City]

FROM [Customers] AS [t0]

WHERE [t0].[CustomerID] LIKE @p0

-- @p0: Input String (Size = 2; Prec = 0; Scale = 0) [A%]

-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

using System.Data.Common;

using System.Collections.Generic;

NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");

var select = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new { 顾客ID = c.CustomerID, 顾客名 = c.Name, 城市 = c.City };

DbCommand cmd = ctx.GetCommand(select);

Response.Write(cmd.CommandText + "<br/>");

foreach (DbParameter parm in cmd.Parameters)

    Response.Write(string.Format("参数名:{0},参数值:{1}<br/>", parm.ParameterName, parm.Value));

Customer customer = ctx.Customers.First();

customer.Name = "zhuye";

IList<object> queryText = ctx.GetChangeSet().ModifiedEntities;

Response.Write(((Customer)queryText[0]).Name);