验证2下拉列表

Question

I wish to ask that how do I compare 2 drop down list value so that they can't be same. <asp:DropDownList ID="DropDownList1" runat="server"> <asp:ListItem Text="Kuala Lumpur International Airport" Value="KUL"></asp:ListItem> <asp:ListItem Text="Kota Kinabalu International Airport" Value="BKI"></asp:ListItem> <asp:ListItem Text="Penang International Airport" Value="PEN"></asp:ListItem> </asp:DropDownList>

`<asp:DropDownList ID="DropDownList2" runat="server">
    <asp:ListItem Text="Kuala Lumpur International Airport" Value="KUL"></asp:ListItem>
    <asp:ListItem Text="Kota Kinabalu International Airport" Value="BKI"></asp:ListItem>
    <asp:ListItem Text="Penang International Airport" Value="PEN"></asp:ListItem> </asp:DropDownList>`

How do I do that so that 2 values won't be the same. Like when user select Kuala Lumpur International Airport in DropDownList1 they can't select Kuala Lumpur International Airport in DropDownList2. Thanks for everyone that help. :)

Answer 1

You can use CompareValidator

<asp:CompareValidator ID="Validator"
        runat="server" 
        ControlToValidate="DropDownList1" 
        ControlToCompare="DropDownList2" 
        ErrorMessage="Please select a different airport." 
        Type="String" 
        Operator="NotEqual"/>