DataTable dt = DBHelper.GetDataTable(sql);
            //添加列名
            DataColumn dc = new DataColumn();
            dc.ColumnName = "月用电量";
            DataColumn dc2 = new DataColumn();
            dc2.ColumnName = "年用电量";
            dt.Columns.Add(dc);
            dt.Columns.Add(dc2);
            DataTable dt2 = null;
            DataTable dt3 = null;
            string times, msql;
            DateTime timess;
            for (int m = 0; m < dt.Rows.Count; m++)
            {
                times = dt.Rows[m]["Datatime"].ToString(); //记录时间
                timess = Convert.ToDateTime(times);
                msql = "select sum(ElectricityConsumption) as 月用电量 From OF_Node_Report_Elec  where NodeID = "+dt.Rows[m]["NodeID"].ToString()+" and Datatime <= '" + times + "' and Datatime >= '" + timess.Year + "/" + timess.Month + "/01'";
                dt2 = DBHelper.GetDataTable(msql);
                dt.Rows[m]["月用电量"] = dt2.Rows[0]["月用电量"];
                msql = "select sum(ElectricityConsumption) as 年用电量 From OF_Node_Report_Elec where NodeID = " + dt.Rows[m]["NodeID"].ToString() + " and Datatime <= '" + times + "' and Datatime >= '" + timess.Year + "/01/01'";
                dt3 = DBHelper.GetDataTable(msql);
                dt.Rows[m]["年用电量"] = dt3.Rows[0]["年用电量"];
                dt2.Clear();
                dt3.Clear();
            }