C#中DataTable实现行列转换的方法

protected void Page_Load(object sender, EventArgs e){  if (!IsPostBack)  {   DataTable tt = GetCrossTable(CreateDT());   GridView1.DataSource = tt;   GridView1.DataBind();  }}//创建DataTableprotected DataTable CreateDT(){  DataTable tblDatas = new DataTable("Datas");  //数据列  tblDatas.Columns.Add("姓名", Type.GetType("System.String"));  tblDatas.Columns.Add("科目", Type.GetType("System.String"));  tblDatas.Columns.Add("分数", Type.GetType("System.Int32"));  tblDatas.Rows.Add(new object[] { "张三", "语文", 89 });  tblDatas.Rows.Add(new object[] { "张三", "数学", 90 });  tblDatas.Rows.Add(new object[] { "张三", "英语", 79 });  tblDatas.Rows.Add(new object[] { "张三", "地理", 70 });  tblDatas.Rows.Add(new object[] { "张三", "生物", 95 });  tblDatas.Rows.Add(new object[] { "李四", "语文", 87 });  tblDatas.Rows.Add(new object[] { "李四", "英语", 86 });  tblDatas.Rows.Add(new object[] { "李四", "地理", 82 });  tblDatas.Rows.Add(new object[] { "王五", "语文", 81 });  tblDatas.Rows.Add(new object[] { "王五", "数学", 70 });  tblDatas.Rows.Add(new object[] { "王五", "英语", 88 });  tblDatas.Rows.Add(new object[] { "王五", "生物", 96 });  return tblDatas;}/// <summary>/// 将DataTable的第二列的值转化为列//（即将原来的行表，转化成交叉表，没有对应值则默认"0"）/// </summary>/// <param name="dt">必须三列，第三列为值</param>/// <returns></returns>public static DataTable GetCrossTable(DataTable dt){  if (dt == null || dt.Columns.Count != 3 || dt.Rows.Count == 0)  {   return dt;  }  else  {   DataTable result = new DataTable();   result.Columns.Add(dt.Columns[0].ColumnName);   DataTable dtColumns = dt.DefaultView.ToTable("dtColumns", true, dt.Columns[1].ColumnName);   for (int i = 0; i < dtColumns.Rows.Count; i++)   {    string colName;    if (dtColumns.Rows[1][0] is DateTime)    {     colName = Convert.ToDateTime(dtColumns.Rows[i][0]).ToString();    }    else    {     colName = dtColumns.Rows[i][0].ToString();    }    result.Columns.Add(colName);    result.Columns[i + 1].DefaultValue = "0";   }   DataRow drNew = result.NewRow();   drNew[0] = dt.Rows[0][0];   string rowName = drNew[0].ToString();   foreach (DataRow dr in dt.Rows)   {    string colName = dr[1].ToString();    double dValue = Convert.ToDouble(dr[2]);    if (dr[0].ToString().Equals(rowName, StringComparison.CurrentCultureIgnoreCase))    {     drNew[colName] = dValue.ToString();    }    else    {     result.Rows.Add(drNew);     drNew = result.NewRow();     drNew[0] = dr[0];     rowName = drNew[0].ToString();     drNew[colName] = dValue.ToString();    }   }   result.Rows.Add(drNew);   return result;  }}