ว่าด้วยเรื่อง การเรียก datakeys มาใช้ในกรณีบางกรณีครับ

 <asp:TextBox ID="TextBox1" runat="server" Height="21px" Width="111px"></asp:TextBox>
    <asp:Button ID="Button2"
        runat="server" Text="ค้นหา" onclick="Button2_Click" />
        
<!-- Gridview -->
<asp:GridView ID = "myGridview" runat="server" AutoGenerateColumns="false" 
        DataKeyNames="id_student"  OnRowEditing="modEditCommand" Width="476px"   >
<Columns>
 <asp:TemplateField HeaderText="รหัสนักเรียน">
 <ItemTemplate>
 <asp:Label ID="lblstuid" runat="server"  Text='<%# DataBinder.Eval(Container, "DataItem.id_student") %>' ></asp:Label>
 </ItemTemplate>
 </asp:TemplateField>
 
 <asp:TemplateField HeaderText="ชื่อนักเรียน">
 <ItemTemplate>
 <asp:Label ID="lblnamestu" runat="server"  Text='<%# DataBinder.Eval(Container, "DataItem.name_student") %>'></asp:Label>
 </ItemTemplate>
 </asp:TemplateField>
 
 <asp:TemplateField HeaderText="นามสกุลนักเรียน">
 <ItemTemplate>
 <asp:Label ID="lblsurnamestu" runat="server"  Text='<%# DataBinder.Eval(Container, "DataItem.surname_student") %>'></asp:Label>
 </ItemTemplate>
 </asp:TemplateField>
 <asp:ButtonField HeaderText="แก้ไข" CommandName="Edit" Text="view"  />
</Columns>
</asp:GridView>
<!--End Gridview -->

<!--detailsview -->


<asp:DetailsView ID="myDetailView" runat="server" AutoGenerateRows="false"  
        OnItemUpdating ="myDetailsView_ItemUpdating"  
        OnModeChanging="myDetailsView_ModeChanging"   Visible="false" Width="361px"> 
<Fields>
<asp:TemplateField HeaderText="id_student">
<ItemTemplate>
<asp:Label ID="lblstudentid" Visible = "false" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.id_student") %>'></asp:Label>
<asp:Label ID="lblstuid" runat ="server" Text='<%# DataBinder.Eval(Container, "DataItem.id_student") %>' ></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:Label ID ="lblstudentid" Visible ="false" runat ="server" Text='<%# DataBinder.Eval(Container, "DataItem.id_student") %>'></asp:Label>
<asp:TextBox id="txtstuid" size="5" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.id_student") %>' ></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>

<asp:TemplateField HeaderText="ชื่อ">
<ItemTemplate>
<asp:Label ID="lblnamestu" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.name_student") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtnamestu" size="10" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.name_student") %>'></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>

<asp:TemplateField HeaderText="นามสกุล">
<ItemTemplate>
<asp:Label ID ="lblsurnamestu" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.surname_student") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="txtsurnamestu" size="10" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.surname_student") %>'></asp:TextBox> 
</EditItemTemplate>
</asp:TemplateField>
<asp:CommandField ShowEditButton="true" CancelText="Cancle" EditText="Edit" UpdateText="Update" />

</Fields>
</asp:DetailsView>


<br />
    <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="กลับสู่หน้าหลัก" 
        Visible="False" />
        

public partial class WebForm6 : System.Web.UI.Page
    {
        SqlConnection objConn;
        SqlCommand objCmd;
        string strSQL;
        string strStuid = "";
        string search;
        
        void Page_Load(object sender, EventArgs e)
        {
            
            string connection = ConfigurationManager.ConnectionStrings["sql"].ConnectionString;
            objConn = new SqlConnection(connection);
            objConn.Open();
            GridViewBindData();
            

        }
        void GridViewBindData()
        {
            //try to search
            if (search == null)
            {
                strSQL = "Select * From student";
                SqlDataReader dtReader;
                objCmd = new SqlCommand(strSQL, objConn);
                dtReader = objCmd.ExecuteReader();
                //*** BindData to Gridview ***//
                myGridview.DataSource = dtReader;
                myGridview.DataBind();

                dtReader.Close();
                dtReader = null;
            }
            else
            {
                strSQL = "Select * From student WHERE((id_student like '%" + search + "%' OR name_student like '%" + search + "%'))";
                SqlDataReader dtReader;
                objCmd = new SqlCommand(strSQL, objConn);
                dtReader = objCmd.ExecuteReader();
                //*** BindData to Gridview ***//
                myGridview.DataSource = dtReader;
                myGridview.DataBind();

                dtReader.Close();
                dtReader = null;

            }
            

        }

        

        protected void DetailsViewBindData()
        {
            strSQL = "select * from student where id_student = '" + strStuid + "' ";
            SqlDataReader dtReader;
            objCmd = new SqlCommand(strSQL, objConn);
            dtReader = objCmd.ExecuteReader();

            //*** BindData to DetailView ***//
            myDetailView.DataSource = dtReader;
            myDetailView.DataBind();

            dtReader.Close();
            dtReader = null;
        }
        protected void Page_UnLoad()
        {
            objConn.Close();
            objConn = null;
 
        }

        protected void modEditCommand(Object sender, GridViewEditEventArgs e)
        {
            myGridview.Visible = false;
            strStuid = myGridview.DataKeys[e.NewEditIndex].Value.ToString();
            myDetailView.Visible = true;
            DetailsViewBindData();
        }
        protected void myDetailsView_ModeChanging(Object sender, DetailsViewModeEventArgs e)
        {

            switch (e.NewMode)
            {
                case DetailsViewMode.Edit:
                    Label lblstuid = (Label)(myDetailView.FindControl("lblstuid"));
                    strStuid = lblstuid.Text;
                    myDetailView.ChangeMode(DetailsViewMode.Edit);
                    DetailsViewBindData();
                    break;
                case DetailsViewMode.ReadOnly:
                    myDetailView.ChangeMode(DetailsViewMode.ReadOnly);
                    myDetailView.Visible = false;
                    myGridview.Visible = true;
                    GridViewBindData();
                    break;
            }
        }

        protected void myDetailsView_ItemUpdating(Object sender, DetailsViewUpdateEventArgs e)
        {
            
            Label lblstudentid = (Label)(myDetailView.FindControl("lblstudentid"));
            strStuid = lblstudentid.Text;
            
            TextBox txtstuid = (TextBox)(myDetailView.FindControl("txtstuid"));
            
            TextBox txtnamestu = (TextBox)(myDetailView.FindControl("txtnamestu"));
            
            TextBox txtsurnamestu = (TextBox)(myDetailView.FindControl("txtsurnamestu"));


            strSQL = "UPDATE student SET " +
           " id_student = '" + txtstuid.Text + "' " +
           " ,name_student = '" + txtnamestu.Text + "' " +
           " ,surname_student = '" + txtsurnamestu.Text + "' " +
           " WHERE id_student = '" + strStuid + "' ";

            objCmd = new SqlCommand(strSQL, objConn);
            objCmd.ExecuteNonQuery();
            string jv = "<script language=\"javascript\"> alert(\"แก้ไขข้อมูลเรียบร้อย\");</script>";
            ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "ABC", jv, false);
            myDetailView.ChangeMode(DetailsViewMode.ReadOnly);
            DetailsViewBindData();
            Button1.Visible = true;


        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            myDetailView.Visible = false;
            myGridview.Visible = true;
            GridViewBindData();
            Button1.Visible = false;
        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            search = TextBox1.Text;
            GridViewBindData();
            myGridview.Visible = true;
            myDetailView.Visible = false;
        }


    }