如何实现GridView1查询出来数据根据查询内容改变颜色

Question

  用的数据动态绑定
protected void Page_Load(object sender, EventArgs e)
    {
       string sqlstr,water_dah;
        if (Request.QueryString["dah"].ToString().Trim()== null)
        {
            Response.Write("没有查到记录");
            Response.End();        }
        else
        {
                sqlstr = "select  * from record";
                string connectionstring = "保密";
                SqlConnection conn1 = new SqlConnection(connectionstring);
                SqlCommand cmd = new SqlCommand(sqlstr, conn1);
                conn1.Open();
                GridView1.DataSource = cmd.ExecuteReader();
                GridView1.DataBind();
            }
            dd.Close();
        }    }//我在record表一个字段  color_no,用来显示查询出来数据行颜色, 
//当color_no=1查询出来该行字体显示为 #FFFFFF 
//当color_no=2查询出来该行字体显示为 #000000 
//当color_no=3查询出来该行字体显示为 #999999 
//改如何使用下面函数 要在GridView1写什么事件，如何调用color_no值？？？？ public string getColor(string color_no)
        {
                switch (color_no)
               {
                          case "1":
                              return "#FFFFFF";
                              break;
                          case "2":
                              return "#000000";
                              break;
                          case "3":
                              return "#999999";
                              break;                }
         }