<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" Height="201px"
        Width="605px" AllowPaging="True" PageSize="20"  OnPageIndexChanging="GridView1_PageIndexChanging"
         OnRowDataBound="GridView1_RowDataBound">
        <Columns>
            <asp:TemplateField HeaderText="会员名" SortExpression="userid" > 
             <ItemTemplate>
            
                 <%#Eval("UserID")%>
             
              </ItemTemplate>
            
            </asp:TemplateField>
            <asp:BoundField DataField="totalPoints" HeaderText="积分" />
            <asp:TemplateField HeaderText="总积分">
            <ItemTemplate>
<%
 [color=#FF0000] string sql="select * from userinfo where userid='"+ (想得到<%#Eval("UserID")%>的值)+"'" [/color]
%>
           
            </ItemTemplate>
            </asp:TemplateField>
            
        </Columns>
    </asp:GridView>

  protected void Page_Load(object sender, EventArgs e)
        {
           if (!IsPostBack)
            {
                DataBind();
            }
        }
       //数据绑定方法
        public void DataBind()
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Test;User ID=sa;Password=123456");
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = con;
            con.Open();
            cmd.CommandText = "select * from Tb1 ";
            DataTable dt = new DataTable();
            dt.Load(cmd.ExecuteReader());
            con.Close();
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }

------解决方案--------------------
后台cs页面指定datasource。确定调用用了GridView的databind()方法。前台用<%# %>标记。再如楼上等人所说，绑定字段就成功啦。