C#中DataTable实现行列转换的方法

本文实例讲述了c#中datatable实现行列转换的方法。分享给大家供大家参考。具体实现方法如下：

protected void page_load(object sender, eventargs e)
{
  if (!ispostback)
  {
   datatable tt = getcrosstable(createdt());
   gridview1.datasource = tt;
   gridview1.databind();
  }
}
//创建datatable
protected 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;
  }
}

希望本文所述对大家的c#程序设计有所帮助。