比较两个DataTable中不同的记录，且合并两个DataTable的列显示，有图

    protected void Page_Load(object sender, EventArgs e)    {        creatDataTable();            }    protected void Button1_Click(object sender, EventArgs e)    {        DataTable DataTableA = ViewState["datatable1"] as DataTable;        DataTable DataTableB = ViewState["datatable2"] as DataTable;        DataTableB.Columns.Add("flag", typeof(String));        DataTableB.Columns["flag"].DefaultValue = "×";        DataView dv1 = DataTableA.DefaultView;        DataView dv2 = DataTableB.DefaultView;        foreach (DataRowView drv1 in dv1)        {            dv2.RowFilter = " id = '" + drv1["id"].ToString() + "'";            if (dv2.Count > 0)            {                if (CompareUpdate(drv1, dv2[0]))//比较是否相同                {                    dv2[0].Row["flag"] = "√";                }                else                {                    dv2[0].Row["flag"] = "×";                }            }        }        GridView3.DataSource = MergeDataTable(DataTableA,DataTableB);        GridView3.DataBind();    }    #region 创建测试DataTable    protected void creatDataTable()    {        //第一步 先初始化数据         DataTable dtA = new DataTable();        dtA.Columns.Add("id", typeof(int));        dtA.Columns.Add("name", typeof(string));        dtA.Rows.Add(1, "a");        dtA.Rows.Add(2, "b");        dtA.Rows.Add(3, "c");        dtA.Rows.Add(4, "d");        DataTable dtB = dtA.Clone();        dtB.Rows.Add(1, "a");        dtB.Rows.Add(2, "d");        dtB.Rows.Add(3, "e");        dtB.Rows.Add(4, "f");        GridView1.DataSource = dtA;        GridView1.DataBind();        GridView2.DataSource = dtB;        GridView2.DataBind();        ViewState["datatable1"] = dtA;        ViewState["datatable2"] = dtB;    }    #endregion     #region 比较数据行是否相同    /// <summary>    /// 比较数据行是否相同    /// </summary>    /// <param name="dr1"></param>    /// <param name="dr2"></param>    /// <returns></returns>    private static bool CompareUpdate(DataRowView dr1, DataRowView dr2)    {        //行里只要有一项不一样，整个行就不一样,无需比较其它        object val1;        object val2;        for (int i = 1; i < dr1.Row.ItemArray.Length; i++)        {            val1 = dr1[i];            val2 = dr2[i];            if (!val1.Equals(val2))            {                return false;            }        }        return true;    }    #endregion     #region 合并两个DataTable列    /// <summary>    /// 合并两个DataTable列    /// </summary>    /// <param name="dt1"></param>    /// <param name="dt2"></param>    /// <returns></returns>    public static DataTable MergeDataTable(DataTable dt1, DataTable dt2)    {        //定义dt的行数         int dtRowCount = 0;        //dt的行数为dt1或dt2中行数最大的行数         if (dt1.Rows.Count > dt2.Rows.Count)        {            dtRowCount = dt1.Rows.Count;        }        else        {            dtRowCount = dt2.Rows.Count;        }        DataTable dt = new DataTable();        //向dt中添加dt1的列名         for (int i = 0; i < dt1.Columns.Count; i++)        {            dt.Columns.Add(dt1.Columns[i].ColumnName + "1");        }        //向dt中添加dt2的列名         for (int i = 0; i < dt2.Columns.Count; i++)        {            dt.Columns.Add(dt2.Columns[i].ColumnName + "2");        }        for (int i = 0; i < dtRowCount; i++)        {            DataRow row = dt.NewRow();            for (int j = 0; j < dt.Columns.Count; j++)            {                for (int k = 0; k < dt1.Columns.Count; k++) { if ((dt1.Rows.Count - 1) >= i) { row[k] = dt1.Rows[i].ItemArray[k]; } }                for (int k = 0; k < dt2.Columns.Count; k++) { if ((dt2.Rows.Count - 1) >= i) { row[dt1.Columns.Count + k] = dt2.Rows[i].ItemArray[k]; } }            }            dt.Rows.Add(row);        }        return dt;    }    #endregion