Validate DropDownList Asp.net

http://msmvps.com/blogs/simpleman/archive/2005/07/18/57948.aspx
<form id="Form1" method="post" runat="server">

< FONT>   <asp:DropDownList id="DropDownList1" runat="server">
       <asp:ListItem Value="-1">--> Choose  <--<!--asp:ListItem>
       <asp:ListItem Value="1">Lebanon<!--asp:ListItem>
       <asp:ListItem Value="2">Kuwait<!--asp:ListItem>
   </<!--asp:DropDownList>
   <asp:RequiredFieldValidator id="RequiredFieldValidator1" 
       runat="server" ErrorMessage="You must select a valid option"
       ControlToValidate="DropDownList1" InitialValue="-1" 
       Display="Dynamic" />
<!--<P>
    <asp:Button id="Button1" runat="server" Text="Post Back" />
<<!--<!--P>
<!--<form>

Add javascript Alert for Delete Linkbutton In Gridview

http://www.dotnetspider.com/resources/23154-Adding-Javascript-Alert-for-Delete-button.aspx

Event of GridView

OnRowDataBound=”GridView1_RowDataBound”

Code behind:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        //add  javascript alert for delete link button
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            LinkButton l = (LinkButton)e.Row.FindControl(“lbtnDeleteGrid”);
            l.Attributes.Add(“onclick”, “return confirm(‘Ban có muốn xóa ngày này không ?’)”);
        }

    }