private void PopulateReport()
        {
            List<ListItems> siteData = new List<ListItems>();
            DataTable dt = GetAllData4();

            foreach (DataRow dr in dt.Rows)
            {
               siteData.Add(new ListItems(int.Parse(dr["MainId"].ToString()),dr["MainName"].ToString(),int.Parse(dr["SecondId"].ToString()),dr["SecondName"].ToString(),int.Parse(dr["ThirdId"].ToString()),dr["ThirdName"].ToString()));

function CheckEmail() {
            var email = document.getElementById('txtEmail');
            var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/ ;
            if (!filter.test(email.value)) {
                alert('Please provide a valid email address');
                return false;
            }
            alert('email address is Ok');
            return true;