Use of RequiredFieldValidator and CompareValidator in ASP.NET

RequiredFieldValidator Control: On using this control we can raise an error message when a field in blank or null, i.e., we can define a field as mandatory.

CompareValidator Contro: This control help us to compare value of one field to another field and raise error message based on the condition we defined.

Below is the sample code where we validate StartDate and EndDate for null values using RequiredFieldValidator and compare Startdate with Enddate value using CompareValidator.

<tr>
<td colspan ="6" rowspan ="3" align ="left"><asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="StartDatePr" ErrorMessage="Start Date should not be null." Display ="Dynamic"></asp:RequiredFieldValidator></td>
</tr>
<tr>
<td colspan ="6" rowspan ="3" align ="left"><asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" ControlToValidate="EndDatePr" ErrorMessage="End Date should not be null." Display ="Dynamic"></asp:RequiredFieldValidator></td>
</tr>
<tr>
<td colspan ="6" rowspan ="3" align ="left"><asp:CompareValidator ID="CompareValidator1" runat="server" ControlToCompare="StartDatePr" ControlToValidate="EndDatePr" ErrorMessage="End Date should be greater than Start Date." Operator="GreaterThan" Type="Date" Display ="Dynamic"></asp:CompareValidator></td>
</tr>
</table>