Check Exist or not

 String qryChkExist = "SELECT isnull(column_name,'') as Article_alias from Table_Name where column_name='" + txtalias.text.tostring().trim()+ "'";

 String ChkRecord = (String)SqlHelper.ExecuteScalar(ConnectionString, CommandType.Text, qryChkExist);
        if (ChkRecord != null)
        {
            if (ChkRecord != "")
            {
                lblMsg.Text = "Another Alias with this Name already exists. Please choose another Alias.";
                return;
            }
        }