LABEL BOUND IN GRIDVIEW AND GRIDVIEWROWDATABOUND

I HAVE A LABEL DOCTOR_ID WHICH IS BOUND IN THE GRIDVIEW.AND THERE ARE OTHER LABEL AND CONTROL PAIRS AS SHOWN IN THE 2ND TEMPLATE FIELD.SOMETHING LIKE THIS:

<asp:TemplateField>
                                            <HeaderTemplate>
                                                Doctor ID</HeaderTemplate>
                                            <ItemTemplate>
                                                <asp:Label ID="lblDoctorID" runat="server" Text='<% #DataBinder.Eval(Container,"Dataitem.DOCTOR_ID") %>'
                                                    CssClass="small">
                                                </asp:Label>
                                            </ItemTemplate>
     </asp:TemplateField>
 <asp:TemplateField>
                                            <HeaderTemplate>
                                                Profile</HeaderTemplate>
                                            <ItemTemplate>
                                                <asp:DropDownList ID="ddlCategory" runat="server" CssClass="dtext" Width="100px">
                                                </asp:DropDownList>
                                                <asp:Label ID="lblCategory" runat="server" Visible="false" CssClass="small"></asp:Label>
                                            </ItemTemplate>
                                        </asp:TemplateField>

NOW AT GRIDVIEW'S ROWDATABOUND EVENT,FOR EVERY ROW'S DOCTOR_ID,I WANNA CHECK IF RECORD EXISTS FOR IT IN THE TABLE.IF YES,I WANT TO set the text property of lblCategory and MAKE THE lblCategory VISIBLE.How to do it ,takin performance into consideration?

Thanks in Advance:)

Thanks and Regards,
Hoosha Boosha