C# asp.net required field validators code example
Example: asp only trigger specific requiredfieldvalidator
<asp:textbox id="AgeTextBox"
runat="Server">
</asp:textbox>
<asp:requiredfieldvalidator id="RequiredFieldValidator1"
controltovalidate="AgeTextBox"
validationgroup="PersonalInfoGroup"
errormessage="Enter your age."
runat="Server">
</asp:requiredfieldvalidator>
<br /><br />
<!--When Button1 is clicked, only validation
controls that are a part of PersonalInfoGroup
are validated.-->
<asp:button id="Button1"
text="Validate"
causesvalidation="true"
validationgroup="PersonalInfoGroup"
runat="Server" />