protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                DataTable dt2 = new DataTable();
                dt2.Columns.Add("id");
                dt2.Columns.Add("name");
                dt2.Rows.Add("0001", "name1");
                dt2.Rows.Add("0002", "name3");
                dt2.Rows.Add("0004", "name4");
                GridView2.DataSource = dt2;
                GridView2.DataBind();

                DataTable dt = new DataTable();
                dt.Columns.Add("id");
                dt.Columns.Add("name");
                dt.Rows.Add("0001", "name1");
                dt.Rows.Add("0002", "name2");
                dt.Rows.Add("0003", "name3");

                GridView1.DataSource = dt;
                GridView1.DataBind();


                // 把多出的行的背景色变成红色
                if (GridView1.Rows.Count > GridView2.Rows.Count)
                {
                    for (int i = GridView2.Rows.Count; i < GridView1.Rows.Count; i++)
                    {
                        GridView1.Rows[i].BackColor = Color.Red;
                    }
                }
                else if (GridView1.Rows.Count < GridView2.Rows.Count)
                {
                    for (int i = GridView1.Rows.Count; i < GridView2.Rows.Count; i++)
                    {
                        GridView2.Rows[i].BackColor = Color.Red;
                    }
                }


            }
        }

        protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            // 数据绑定的时候根据现在的值去跟另一个比较，不同的背景色设置红色
            // 注意:GridView2要先完成数据绑定，然后在GridView1_RowDataBound的绑定事件里去比较
            // 也可以在两个都完成绑定后，通过双重循环来直接遍历gridview比较
            if (e.Row.RowType != DataControlRowType.DataRow)
            { return; }
            if (e.Row.RowIndex >= GridView2.Rows.Count)
            {
                return;
            }
            for (int i = 0; i < e.Row.Cells.Count; i++)
            {
                DataRowView drv = (DataRowView)e.Row.DataItem;
                if (!GridView2.Rows[e.Row.RowIndex].Cells[i].Text.Equals(drv.Row[i].ToString()))
                {
                    GridView2.Rows[e.Row.RowIndex].Cells[i].BackColor = Color.Red;
                    e.Row.Cells[i].BackColor = Color.Red;
                }
            }
        }