/// <summary>

        /// 执行查询语句，返回DataSet

        /// </summary>

        /// <param name="SQLString">查询语句</param>

        /// <returns>DataSet</returns>

        public static DataSet Query(string SQLString)

        {

            using (SqlConnection connection = new SqlConnection(connectionString))

            {

                DataSet ds = new DataSet();

                try

                {

                    connection.Open();

                    SqlDataAdapter command = new SqlDataAdapter(SQLString, connection);

                    command.Fill(ds, "ds");

                }

                catch (System.Data.SqlClient.SqlException ex)

                {

                    throw new Exception(ex.Message);

                }

                return ds;

            }

        }