<asp:DropDownList ID="ddlHero1" runat="server" DataSourceID="ddlDataSource0"                        DataTextField="ChampName" DataValueField="ChamadpName" AutoPostBack="True">
                                    </asp:DropDownList>
                                    <asp:SqlDataSource ID="ddlDataSource0" runat="server"
                                        ConnectionString="<%$ ConnectionStrings:mobamanagerConnectionString 		%>" SelectCommand="SELECT [ChampName] FROM [Champions] WHERE Champname NOT IN (
SELECT [ChampName] FROM [Champions] WHERE Champname=@ddlHero2
UNION
SELECT [ChampName] FROM [Champions] WHERE Champname=@ddlHero3
UNION
SELECT [ChampName] FROM [Champions] WHERE Champname=@ddlHero4
UNION
SELECT [ChampName] FROM [Champions] WHERE Champname=@ddlHero5)">
                                        <SelectParameters>
                                            <asp:ControlParameter ControlID="ddlHero2" Name="ddlHero2"
                                                PropertyName="SelectedValue" />
                                            <asp:ControlParameter ControlID="ddlHero3" Name="ddlHero3"
                                                PropertyName="SelectedValue" />
                                            <asp:ControlParameter ControlID="ddlHero4" Name="ddlHero4"
                                                PropertyName="SelectedValue" />
                                            <asp:ControlParameter ControlID="ddlHero5" Name="ddlHero5"
                                                PropertyName="SelectedValue" />
                                        </SelectParameters>
                                    </asp:SqlDataSource>

END CODE
-----------
This process is repeated another 4 times with different queries for each DDL, but the procedure is identical.