A validation group enables you to group related form fields together. : ValidationGroup « Validation « ASP.NET Tutorial

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    void btnLogin_Click(Object sender, EventArgs e)
    {
        if (Page.IsValid)
            lblLoginResult.Text = "Log in successful!";
    }

    void btnRegister_Click(Object sender, EventArgs e)
    {
        if (Page.IsValid)
            lblRegisterResult.Text = "Registration successful!";
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Show Validation Groups</title>
</head>
<body>
    <form id="form1" runat="server">
    <div class="column">
    <fieldset>
    <legend>Login</legend>
    <asp:Label
        id="lblUserName"
        Text="User Name:"
        AssociatedControlID="txtUserName"
        Runat="server" />
    <br />
    <asp:TextBox
        id="txtUserName"
        Runat="server" />
    <asp:RequiredFieldValidator
        id="reqUserName"
        ControlToValidate="txtUserName"
        Text="(Required)"
        ValidationGroup="LoginGroup"
        Runat="server" />
    <br /><br />
    <asp:Label
        id="lblPassword"
        Text="Password:"
        AssociatedControlID="txtPassword"
        Runat="server" />
    <br />
    <asp:TextBox
        id="txtPassword"
        TextMode="Password"
        Runat="server" />
    <asp:RequiredFieldValidator
        id="reqPassword"
        ControlToValidate="txtPassword"
        Text="(Required)"
        ValidationGroup="LoginGroup"
        Runat="server" />
    <asp:Button
        id="btnLogin"
        Text="Login"
        ValidationGroup="LoginGroup"
        Runat="server" OnClick="btnLogin_Click" />
    </fieldset>

    <asp:Label
        id="lblLoginResult"
        Runat="server" />
    </div>

    <div class="column">
    <fieldset>
    <legend>Register</legend>
    <asp:Label
        id="lblFirstName"
        Text="First Name:"
        AssociatedControlID="txtFirstName"
        Runat="server" />
    <br />
    <asp:TextBox
        id="txtFirstName"
        Runat="server" />
    <asp:RequiredFieldValidator
        id="reqFirstName"
        ControlToValidate="txtFirstName"
        Text="(Required)"
        ValidationGroup="RegisterGroup"
        Runat="server" />
    <br /><br />
    <asp:Label
        id="lblLastName"
        Text="Last Name:"
        AssociatedControlID="txtLastName"
        Runat="server" />
    <br />
    <asp:TextBox
        id="txtLastName"
        Runat="server" />
    <asp:RequiredFieldValidator
        id="reqLastName"
        ControlToValidate="txtLastName"
        Text="(Required)"
        ValidationGroup="RegisterGroup"
        Runat="server" />
    <br /><br />
    <asp:Button
        id="btnRegister"
        Text="Register"
        ValidationGroup="RegisterGroup"
        Runat="server" OnClick="btnRegister_Click" />
    </fieldset>

    <asp:Label
        id="lblRegisterResult"
        Runat="server" />

    </div>

    </form>
</body>
</html>

8.12.ValidationGroup
	8.12.1.	A validation group enables you to group related form fields together.
	8.12.2.	Validation Groups Demo
	8.12.3.	Group based validation (C#)
	8.12.4.	Two validation groups
	8.12.5.	Using the ValidationGroup property (VB)