Check For date in datagrid

@Maulik
I have a gridview, which is as below

<asp:GridView ID="gvShortStayRate" runat="server" AutoGenerateColumns="False"
BorderColor="Black" BorderWidth="1px" DataKeyNames="Id"
DataSourceID="ShortTermRateDS" OnRowCommand="gvShortStayRate_RowCommand"
ShowFooter="True">
<Columns>

<asp:TemplateField HeaderText="First night">
<EditItemTemplate>
<asp:TextBox ID="Editstart_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("start_date") %>' Width="65px" />
<asp:CalendarExtender ID="calstart_date" runat="server" Enabled="True" Format="dd/MM/yyyy"
PopupButtonID="img_calendarstart" TargetControlID="Editstart_date"></asp:CalendarExtender>
<asp:Image ID="img_calendarstart" runat="server" ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVEditStartDate" runat="server" ControlToValidate="Editstart_date"
ErrorMessage="*" ValidationGroup="Edit"></asp:RequiredFieldValidator>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Insertstart_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("start_date") %>' Width="65px" />
<asp:CalendarExtender ID="calInsertstart_date" runat="server" Enabled="True"
Format="dd/MM/yyyy" PopupButtonID="imgcalendarInsertstart"
TargetControlID="Insertstart_date"></asp:CalendarExtender>
<asp:Image ID="imgcalendarInsertstart" runat="server"
ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVInsertStartDate" runat="server"
ControlToValidate="Insertstart_date" ErrorMessage="*" ValidationGroup="Insert"></asp:RequiredFieldValidator>
</FooterTemplate>
<ItemTemplate>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Last night">
<EditItemTemplate>
<asp:TextBox ID="Editend_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("end_date") %>' Width="65px" />
<asp:CalendarExtender ID="calEditend_date" runat="server" Enabled="True" Format="dd/MM/yyyy"
PopupButtonID="imgcalendarEditend" TargetControlID="Editend_date"></asp:CalendarExtender>
<asp:Image ID="imgcalendarEditend" runat="server" ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVEditEndDate" runat="server" ControlToValidate="Editend_date"
ErrorMessage="*" ValidationGroup="Edit"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVEnddate" runat="server" ControlToCompare="EditStart_date"
ControlToValidate="Editend_date" ErrorMessage="end date should be greater than start date"
Operator="GreaterThan" ValidationGroup="Edit"></asp:CompareValidator>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Insertend_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("end_date") %>' Width="65px" />
<asp:CalendarExtender ID="calInsertend_date" runat="server" Enabled="True"
Format="dd/MM/yyyy" PopupButtonID="imgcalendarInserttend"
TargetControlID="Insertend_date"></asp:CalendarExtender>
<asp:Image ID="imgcalendarInserttend" runat="server"
ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVInsertEndDate" runat="server"
ControlToValidate="Insertend_date" ErrorMessage="*" ValidationGroup="Insert"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVInsertEnddate" runat="server"
ControlToCompare="Insertstart_date" ControlToValidate="Insertend_date"
ErrorMessage="end date should be greater than start date"
Operator="GreaterThan" ValidationGroup="Insert"></asp:CompareValidator>
</FooterTemplate>
<ItemTemplate>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Weekly rate">
<EditItemTemplate>
<asp:TextBox ID="Editweekly_rate" runat="server" Height="15px"
Text='<%# Bind("weekly_rate") %>' Width="50px" />
<asp:RequiredFieldValidator ID="RFVWeeklyRate" runat="server" ControlToValidate="Editweekly_rate"
ErrorMessage="*" ValidationGroup="Edit"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVWeeklyRate" runat="server" ControlToValidate="Editweekly_rate"
ErrorMessage="Enter Valid Rate" Operator="DataTypeCheck" Type="Double"
ValidationGroup="Edit"></asp:CompareValidator>
</EditItemTemplate>
<FooterTemplate>
<asp:TextBox ID="Insertweekly_rate" runat="server" Height="15px"
Text='<%# Bind("weekly_rate") %>' Width="50px" />
<asp:RequiredFieldValidator ID="RFVInsertWeeklyRate" runat="server"
ControlToValidate="Insertweekly_rate" ErrorMessage="*" ValidationGroup="Insert"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVInsertWeeklyRate" runat="server"
ControlToValidate="Insertweekly_rate" ErrorMessage="Enter Valid Rate"
Operator="DataTypeCheck" Type="Double" ValidationGroup="Insert"></asp:CompareValidator>
</FooterTemplate>
<ItemTemplate>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Commands">
<EditItemTemplate>
<asp:Button ID="Update" runat="server" CommandArgument='<%#Eval("id") %>'
CommandName="Update" Text="Update" ValidationGroup="Edit" />
<asp:Button ID="Cancel" runat="server" CommandName="Cancel" Text="Cancel" />
</EditItemTemplate>
<FooterTemplate>
<asp:Button ID="Insert" runat="server" CommandName="InsertNew" Text="Insert"
ValidationGroup="Insert" />
</FooterTemplate>
<ItemTemplate>
<asp:Button ID="Edit" runat="server" CommandName="Edit" Text="Edit" />
<asp:Button ID="Delete" runat="server" CommandName="Delete" Text="Delete" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
<EmptyDataTemplate>

First night:<asp:TextBox ID="NoDatastart_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("start_date") %>' Width="65px" />
<asp:CalendarExtender ID="calNoDatastart_date" runat="server" Enabled="True" Format="dd/MM/yyyy"
OnClientDateSelectionChanged="DateSelected" PopupButtonID="imgcalendarNodatatstart" TargetControlID="NoDatastart_date"></asp:CalendarExtender>
<asp:Image ID="imgcalendarNodatatstart" runat="server" ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVNoDatastartdate" runat="server" ControlToValidate="NoDatastart_date"
ErrorMessage="*" ValidationGroup="NoDataInsert"></asp:RequiredFieldValidator>
Last night:<asp:TextBox ID="NoDataend_date" runat="server" Height="15px" ReadOnly="True"
Text='<%# Bind("end_date") %>' Width="65px" />
<asp:CalendarExtender ID="calNoDataend_date" runat="server" Enabled="True" Format="dd/MM/yyyy"
PopupButtonID="imgcalendarNodatatend" TargetControlID="NoDataend_date"></asp:CalendarExtender>
<asp:Image ID="imgcalendarNodatatend" runat="server"
ImageUrl="Images/Calendar_scheduleHS.png" />
<asp:RequiredFieldValidator ID="RFVNodataEndDate" runat="server" ControlToValidate="NoDataend_date"
ErrorMessage="*" ValidationGroup="NoDataInsert"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVNodataEnddate" runat="server" ControlToCompare="NoDatastart_date"
ControlToValidate="NoDataend_date" ErrorMessage="end date should be greater than start date"
Operator="GreaterThan" ValidationGroup="NoDataInsert"></asp:CompareValidator>
Weekly rate:<asp:TextBox ID="NoDataweekly_rate" runat="server" Height="15px"
Text='<%# Bind("weekly_rate") %>' Width="50px" />
<asp:RequiredFieldValidator ID="RFVNodataWeeklyRate" runat="server" ControlToValidate="NoDataweekly_rate"
ErrorMessage="*" ValidationGroup="NoDataInsert"></asp:RequiredFieldValidator>
<asp:CompareValidator ID="CVNoDataWeeklyRate" runat="server" ControlToValidate="NoDataweekly_rate"
ErrorMessage="Enter Valid Rate" Operator="DataTypeCheck" Type="Double" ValidationGroup="NoDataInsert"></asp:CompareValidator>
</EmptyDataTemplate>
<RowStyle BorderColor="Beige" BorderWidth="1px" />
</asp:GridView>

User can enter startdate,enddate and price.Once user clicks on Insert this record is saved in database.
What i have to do now is check whether startdate,enddate and price is entered for 12 months (365 days) or check if there is any missing days for which price is not entered and alert user.