gridview 增加行，进行数据汇总

DataRow dr  =  table1.NewRow();
           // 1是把所有列进行汇总
            // for (int i = 1; i < table1.Columns.Count; i++)
            //  {
                //  dr = table1.Compute("Sum(" + table1.Columns.ColumnName + ")", "true");   
             // }


            // 仅对需要的列进行汇总
              decimal  xxx  =   0 ;
             decimal  xxx1  =   0 ;
              for  ( int  i  =   1 ; i  <  table1.Rows.Count; i ++ )
              {
                 
                 xxx  += Convert.ToDecimal(table1.Rows["衣服用费"]);
                 dr[1]=xxx;
                 
                 xxx1 += Convert.ToDecimal(table1.Rows["住宿费用"]);
                 dr[2] = xxx1;

            }

            table1.Rows.Add(dr);

            GridView1.DataSource  =  table1;