in .net I am using dropdownbox which is bind to database but database contains same values how to reduce it

<table id="1"> <tr> <td class="style41"> <asp:DropDownList ID="DropDownList13" runat="server" DataSourceID="SqlDataSource14" DataTextField="Category" DataValueField="Category" Height="23px" Width="124px" AutoPostBack="True"> </asp:DropDownList> <asp:SqlDataSource ID="SqlDataSource14" runat="server" ConnectionString="<%$ ConnectionStrings:saConnectionString %>" SelectCommand="SELECT [Category] FROM [Unit_Master] WHERE ([LossType] = @LossType)"> <SelectParameters> <asp:ControlParameter ControlID="DropDownLi ...