DropDown List Validation

I nee开发者_运维百科d to perform a validation to check whether a TextBox value is empty on Dropown list selected Index change using validation controls in asp.net

I hope this will work fine.

    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <asp:DropDownList ID="DropDownList1" runat="server" CausesValidation="true" AutoPostBack="true">
    </asp:DropDownList>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator1" ControlToValidate="TextBox1" runat="server" ErrorMessage="Please Enter the Value"></asp:RequiredFieldValidator>