DataTable 队列转换 将原来的行表转化成交叉表，无对应值赋默认值，用于统计显示或报表

    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;        }    }