/// <summary>
        /// 复制DataTable
        /// </summary>
        /// <param name="copyDt">数据源</param>
        /// <param name="tableName">新DataTable名称</param>
        /// <returns>复制后的DataTable</returns>
        private DataTable CopyDataTable(DataTable copyDt, string tableName)
        {
            DataTable dt = new DataTable(tableName);
            foreach (DataColumn columm in copyDt.Columns)
            {
                dt.Columns.Add(columm.ColumnName,columm.DataType);
            }

            foreach (DataRow row in copyDt.Rows)
            {
                dt.BeginInit();
                dt.ImportRow(row);
                dt.EndInit();
            }

            return dt;
        }