将 sqlconnection 定义为 static 型,        public static SqlConnection connGlobal = null;
        public static int ConnectDatabase(String strConnection)
        {
            try
            {
                connGlobal = new SqlConnection(strConnection);
                connGlobal.Open();
                return 1;
            }
            catch (Exception e)
            {
                ErrMessage = e.ToString();
                return 0;
            }
        }