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();

        }

    }

}