Linq to sql（三）：增删改（三）

前面创建Linq to sql Classes的时候我们输入名字GuestBook，系统就为我们自动创建了GuestBookDataContext  （你也可以在GuestBook.Designer.cs中找到类定义）。在绑定的时候我们使用查询句法查询留言表中所有留言， 按照发表时间倒序（天哪？这是数据访问吗？好像仅仅定义了一句SQL啊）。在发表留言按钮中， 我们为一个tbGuestBook赋值，然后把它加入留言表，再提交更改，就这样完成了记录的插入。          运行效果如下图：        然后，再创建一个Admin.aspx，前台代码如下： <div>         <asp:Repeater ID="rpt_Message" runat="server" OnItemCommand="rpt_Message_ItemCommand">         <ItemTemplate>         <table width="600px" style="border:solid 1px #666666; font-size:10pt; background-color:#f0f0f0">             <tr>             <td align="left" width="400px">             <%# Eval("Message")%>             </td>             <td align="right" width="200px">             <%# Eval("PostTime")%> - <%# Eval("UserName")%>             </td>             </tr>             <tr>             <td colspan="2" align="right">             <hr width="300px" />             <asp:Button ID="btn_DeleteMessage" runat="server" Text="删除留言" CommandName="DeleteMessage" CommandArgument='<%# Eval("ID")%>'/>             管理员回复：<asp:TextBox runat="server" ID="tb_Reply" TextMode="MultiLine" Width="300px" Text='<%# Eval("Reply")%>'/>             <asp:Button ID="btn_SendReply" runat="server" Text="发表回复" CommandName="SendReply" CommandArgument='<%# Eval("ID")%>'/>             </td>             </tr>                   </table>         <br/>         </ItemTemplate>         </asp:Repeater>     </div>        后台代码：   public partial class Admin : System.Web.UI.Page {     GuestBookDataContext ctx = new GuestBookDataContext("server=xxx;database=GuestBook;uid=xxx;pwd=xxx");             protected void Page_Load(object sender, EventArgs e)     {         if (!IsPostBack)         {             SetBind();         }     }       private void SetBind()     {         rpt_Message.DataSource = from gb in ctx.tbGuestBooks orderby gb.PostTime descending select gb;         rpt_Message.DataBind();     }     protected void rpt_Message_ItemCommand(object source, RepeaterCommandEventArgs e)     {         if (e.CommandName == "DeleteMessage")         {             StreamWriter sw = new StreamWriter(Server.MapPath("log.txt"), true);             ctx.Log = sw;             tbGuestBook gb = ctx.tbGuestBooks.Single(b => b.ID == new Guid(e.CommandArgument.ToString()));             ctx.tbGuestBooks.Remove(gb);             ctx.SubmitChanges();             SetBind();             sw.Close();         }         if (e.CommandName == "SendReply")         {             StreamWriter sw = new StreamWriter(Server.MapPath("log.txt"), true);             ctx.Log = sw;             tbGuestBook gb = ctx.tbGuestBooks.Single(b => b.ID == new Guid(e.CommandArgument.ToString()));             gb.Reply = ((TextBox)e.Item.FindControl("tb_Reply")).Text;             gb.IsReplied = true;             ctx.SubmitChanges();             SetBind();             sw.Close();         }     } }