ต้องการให้ checkboxใน gridview เลือกได้ครั้งเดียวค่ะ ต้องทำอย่างไร asp.net c#

<asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:GridView ID="GvData" runat="server" AutoGenerateColumns="False">
                    <Columns>
                        <asp:BoundField DataField="KEY" />
                        <asp:TemplateField HeaderText="CB1" ItemStyle-HorizontalAlign="Center">
                            <ItemTemplate>
                                <asp:CheckBox runat="server" ID="CB1" OnCheckedChanged="CB1_CheckedChanged" AutoPostBack="true" />
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="CB2" ItemStyle-HorizontalAlign="Center">
                            <ItemTemplate>
                                <asp:CheckBox runat="server" ID="CB2" Enabled="true" OnCheckedChanged="CB2_CheckedChanged"
                                    AutoPostBack="true" />
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="CB3" ItemStyle-HorizontalAlign="Center">
                            <ItemTemplate>
                                <asp:CheckBox runat="server" ID="CB3" Enabled="true" OnCheckedChanged="CB3_CheckedChanged"
                                    AutoPostBack="true" />
                            </ItemTemplate>
                        </asp:TemplateField>
                    </Columns>
                </asp:GridView>
            </ContentTemplate>
        </asp:UpdatePanel>

        protected void CB1_CheckedChanged(object sender, EventArgs e)
        {
            GridViewRow gridViewRow = (GridViewRow)(sender as Control).Parent.Parent;
            int index = gridViewRow.RowIndex;

            CheckBox cb1 = (CheckBox)GvData.Rows[index].FindControl("CB1");
            CheckBox cb2 = (CheckBox)GvData.Rows[index].FindControl("CB2");
            CheckBox cb3 = (CheckBox)GvData.Rows[index].FindControl("CB3");

            if (cb1.Checked)
            {
                cb2.Checked = false;
                cb3.Checked = false;
            }
            else
            {

            }
        }

        protected void CB2_CheckedChanged(object sender, EventArgs e)
        {
            GridViewRow gridViewRow = (GridViewRow)(sender as Control).Parent.Parent;
            int index = gridViewRow.RowIndex;

            CheckBox cb1 = (CheckBox)GvData.Rows[index].FindControl("CB1");
            CheckBox cb2 = (CheckBox)GvData.Rows[index].FindControl("CB2");
            CheckBox cb3 = (CheckBox)GvData.Rows[index].FindControl("CB3");

            if (cb2.Checked)
            {
                cb1.Checked = false;
                cb3.Checked = false;
            }
            else
            {

            }
        }

        protected void CB3_CheckedChanged(object sender, EventArgs e)
        {
            GridViewRow gridViewRow = (GridViewRow)(sender as Control).Parent.Parent;
            int index = gridViewRow.RowIndex;

            CheckBox cb1 = (CheckBox)GvData.Rows[index].FindControl("CB1");
            CheckBox cb2 = (CheckBox)GvData.Rows[index].FindControl("CB2");
            CheckBox cb3 = (CheckBox)GvData.Rows[index].FindControl("CB3");

            if (cb3.Checked)
            {
                cb1.Checked = false;
                cb2.Checked = false;
            }
            else
            {

            }
        }