请教高手一问题，DataGrid中想对某一列求和（或平均值），然后结果能显示在这一列的下面。

Question

请教高手一问题，DataGrid中想对某一列求和（或平均值），然后结果能显示在这一列的下面，不知道如何实现？
我查属性，有一个Expression，但不知道如何用，高手们请指点一下。

Answer 1

楼主这个思路可能不行，给你换钟思路：SQL例如有一张人员编制表，部门下有多个科室，每个科室有一定的人数，如下
field1   field2   amount
部门a    系统科    5
部门a    科室2     3
部门b    系统科    4
.........
select * from (
select field1, field2,amount,field1 as tmp1,1 as tmp2 from table1
union
select field1,'小计',sum(amount),field1 , 2 as tmp2 from table1 group by field1
) as t order by t.tmp1,t.tmp2绑定，ok

Answer 2

protected System.Web.UI.WebControls.DataGrid DataGrid1;         /// <summary>         /// 数据来源         /// </summary>         DataSet CreateDataSource()          {              DataTable dt = new DataTable();              DataRow dr;            dt.Columns.Add(new DataColumn("名称", typeof(string)));              dt.Columns.Add(new DataColumn("Value1", typeof(Int32)));              dt.Columns.Add(new DataColumn("Value2", typeof(Int32)));              dt.Columns.Add(new DataColumn("Value3", typeof(Int32)));              dt.Columns.Add(new DataColumn("Value4", typeof(Int32)));              for (int i = 0; i < 10; i++)               {                   dr = dt.NewRow();                dr[0] = i.ToString()+"名称";                   dr[1] = i;                   dr[2] = i+1;                   dr[3] = i+2;                   dr[4] = i+3;                   dt.Rows.Add(dr);              }                DataSet MyData=new DataSet();              MyData.Tables.Add(dt);              return MyData;         }         private void Page_Load(object sender, System.EventArgs e)         {              // 在此处放置用户代码以初始化页面                            DataSet MyData=CreateDataSource();//            DataGrid1.DataSource= MyData;//            DataGrid1.DataBind();              DataTable MyTable=new DataTable();              DataColumn myColum;                 foreach( DataColumn  NowDataColumn in MyData.Tables[0].Columns)              {                   myColum=new  DataColumn();                   myColum.DataType=NowDataColumn.DataType;                   myColum.ColumnName=NowDataColumn.ColumnName;                   MyTable.Columns.Add(myColum);              }              myColum=new  DataColumn();              myColum.DataType=System.Type.GetType("System.Int32");              myColum.ColumnName="每行合计";              MyTable.Columns.Add(myColum);              DataRow  AcountRow;                  int DataColumns=MyData.Tables[0].Columns.Count;              foreach( DataRow  NowRow in  MyData.Tables[0].Rows)              {                   AcountRow=MyTable.NewRow();                   AcountRow.ItemArray=NowRow.ItemArray;                   //每行合计                   GetRowAccount(AcountRow,1,5,DataColumns);                   MyTable.Rows.Add(AcountRow);              }              //生成的合计              AcountRow=MyTable.NewRow();              AcountRow[0]="竖列合计";                  for(int count=1;count<MyTable.Columns.Count;count++)                   foreach (DataRow NowRow in  MyTable.Rows)                   {                       if(!AcountRow.IsNull(count))                       {                            if (!AcountRow.IsNull(count) )                                 AcountRow[count]= Convert.ToInt32(AcountRow[count])+Convert.ToInt32(NowRow[count]);                       }                       else   AcountRow[count]=NowRow[count];;              }              MyTable.Rows.Add(AcountRow);              DataGrid1.DataSource=MyTable;              DataGrid1.DataBind();          }         /// <summary>         /// 每行合计         /// </summary>         private  void  GetRowAccount(DataRow AcountRow,int begincol,int endcol,int accountcol)         {              for(int i=begincol;i<endcol;i++)              {                       if(!AcountRow.IsNull(accountcol))                    {                   if ( !AcountRow.IsNull(i) )                        AcountRow[accountcol]= Convert.ToInt32(AcountRow[accountcol])+Convert.ToInt32(AcountRow[i]);                              }                   else  AcountRow[accountcol]=AcountRow[i];                    }         }

Answer 3

是用表达式和数据绑定 
详细请见
ms-help://MS.VSCC.2003/MS.MSDNQTR.2003FEB.2052/cpref/html/frlrfSystemDataDataColumnClassExpressionTopic.htm