想要在GridView中进行日期验证

朋友们，
我有以下gridview，我想提供日期验证，当我单击更新或插入下拉列表时，selecteditem自动设置为selectedIndex = 0.

Hi friends,
I have a following gridview in that i want to provide date validations and when i click on update or insert the drop down selecteditem is auto set to selectedIndex=0.

<asp:GridView ID="GridView1" runat="server" Width="100%" OnRowUpdating="GridView1_RowUpdating" AutoGenerateColumns="False" CellPadding="1" ForeColor="Black" BackColor="LightGoldenrodYellow" BorderColor="Tan" BorderWidth="1px" BorderStyle="None" CaptionAlign="Top" CellSpacing="1" HorizontalAlign="Center">
                    <Columns>
                        <asp:TemplateField HeaderText="ID">
                            <ItemTemplate>
                                <asp:Label ID="lbl123" runat="server" Text='<%#Eval("id") %>'></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Hospital Name">
                            <ItemTemplate>
                                <asp:Label runat="server" ID="lblHospName" Text='<%#Eval("Hospitalname") %>'></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Hospital Type">
                            <ItemTemplate>
                                <asp:DropDownList runat="server" ID="ddlHospType" EnableViewState="true" >
                                    <asp:ListItem Text="--Select--" Value="0"></asp:ListItem>
                                    <asp:ListItem Text="Private" Value="1"></asp:ListItem>
                                    <asp:ListItem Text="Govt" Value="2"></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Hospital District Name">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtHospDistName" Text='<%#Bind("HopDistName") %>'></asp:TextBox>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:TextBox runat="server" ID="txtHospDistName" Text='<%#Bind("HopDistName") %>'></asp:TextBox>
                            </EditItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Time Of Admission">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtTimeOfAdmin" Text='<%#Bind("TimeOFAdmission") %>'></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Time Of Discharge">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtTimeOfDischarge" Text='<%#Bind("TimeOfDischarge") %>'></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>

                        <asp:TemplateField HeaderText="Claim Status">
                            <ItemTemplate>
                                <asp:DropDownList runat="server" ID="ddlClaimStatus">
                                    <asp:ListItem Text="--Select--" Value="0"></asp:ListItem>
                                    <asp:ListItem Text="Approved" Value="1"></asp:ListItem>
                                    <asp:ListItem Text="Pending" Value="2"></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Date Of Payment">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtDateOfPayment" Text='<%# Bind("DateOfPayment") %>' MaxLength="10"></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Time Takem For Settlement Of Claim">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtTimeTakenForClaimSettlement" Text='<%# Bind("TimeTkanenforSettlementofClaim") %>'></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Float Submitted Date">
                            <ItemTemplate>
                                <asp:TextBox runat="server" ID="txtfsd1" Text='<%#Bind("fsd") %>' MaxLength="10"></asp:TextBox>

                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Edit To Update">
                            <ItemTemplate>
                                <asp:LinkButton ID="btnEditInsert" runat="server" CommandName="Insert" Text="Insert"   OnClientClick="return Submit_Click();" CommandArgument='<%#Container.DataItemIndex %>' />&nbsp;
                                <asp:LinkButton ID="btnEditUpdate" runat="server" CommandName="Update" Text="Update"  OnClientClick="return Submit_Click();"/>&nbsp;
                            </ItemTemplate>
                        </asp:TemplateField>
                    </Columns>

                </asp:GridView>