Sorry……

You should know that "Departments" is another collection nested in the collection of result，So plz nest another GridView inside the ItemTemplate of the outer GridView，and then do databinding:-)

Sample codes：

<asp:GridView id="GridView1" runat="server" AutoGenerateColumns="false" Enabled="true" Visible="true" OnLoad="gvload">

     <Columns>

         <asp:TemplateField HeaderText="FloorName">

            <ItemTemplate><%#Eval("FloorName")%></ItemTemplate>

         </asp:TemplateField>

         <asp:TemplateField HeaderText="Departments">

            <ItemTemplate>

                  <asp:GridView id="GridView1" runat="server" AutoGenerateColumns="false"                   DataSource='<%#Eval("Departments")%'>……>

                  <Columns>

                                <asp:TemplateField HeaderText="Department">

                                                <ItemTemplate>

                                                                <%#Eval("Department")%>

 </ItemTemplate>

 </asp:TemplateField>

                </Columns>

</asp:GridView>

            </ItemTemplate>

         </asp:TemplateField>

     </Columns>

</asp:GridView>