数据结构：
表dep：depid（标识主键），depname（学院名字）
表stu：stuid（标识主键），stuname（学生名字），studepid（depid字段内容）

<%@ Page Language="VB" AutoEventWireup="True" Debug="true"%>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SQLClient" %>
<script runat="server">
      Dim strDropDownListValue as String   
      Dim MyConnection as SQLConnection = New SqlConnection("server=localhost;Initial Catalog=nhlinkin;uid=sa;pwd=")
      Dim MyCommand As SQLDataAdapter

      Sub Page_Load(sender As Object, e As EventArgs) 
          If Not IsPostBack Then 
             BindGrid()
          End If
      End Sub

      Sub BindGrid() 
          Dim MyCommand As SQLDataAdapter = new SQLDataAdapter("SELECT * FROM stu,dep WHERE stu.studepid=dep.depid", MyConnection)
          Dim DS As DataSet = new DataSet()
          MyCommand.Fill(DS,"min") 
          MyDataGrid.DataSource = DS.Tables("min").DefaultView
          MyDataGrid.DataBind()
      End Sub
      Sub MyDataGrid_Paging(sender as Object, e As DataGridPageChangedEventArgs) 
         MyDataGrid.CurrentPageIndex = e.NewPageIndex
         BindGrid()
      End Sub

    Sub MyDataGrid_Edit(Sender As Object, E As DataGridCommandEventArgs)
        Response.Write(e.Item.Cells(0).Text) 
        MyDataGrid.EditItemIndex = CInt(E.Item.ItemIndex)
        strDropDownListValue = Ucase(CType(e.Item.FindControl("lblDepName"), Label).Text)
        BindGrid()
        Response.Write(strDropDownListValue)
    End Sub

    Sub MyDataGrid_Cancel(sender As Object, e As DataGridCommandEventArgs)
        MyDataGrid.EditItemIndex = -1
        BindGrid()      
    End Sub

    Sub MyDataGrid_Delete(sender As Object, e As DataGridCommandEventArgs)
        MyDataGrid.EditItemIndex = -1
        BindGrid()
        Response.Write(e.Item.Cells(0).Text)  
    End Sub

    Sub MyDataGrid_ItemDataBound(s as object, e as DataGridItemEventArgs)
       If e.item.itemType = ListItemType.EditItem Then
          Dim myDropDown as DropDownList
          myDropDown = Ctype(e.Item.FindControl("dropDepName"), DropDownList)
          myDropDown.SelectedIndex =myDropDown.Items.IndexOf(myDropDown.items.findbytext(strDropDownListValue))
       End If
    End Sub

    Private Function BindDropDownList()
        Dim myCommand As sqlCommand = New sqlCommand("SELECT * FROM dep ORDER BY depID ASC", myConnection)
        myConnection.Open()
        Return myCommand.ExecuteReader(CommandBehavior.CloseConnection)
    End Function
</script>

<form runat="server">
<asp:DataGrid id="MyDataGrid" 
           runat="server"
           AutoGenerateColumns="False"
           Width="200"
           AllowPaging="True" 
           PageSize="5" 
           OnPageIndexChanged="MyDataGrid_Paging" 
           OnEditCommand="MyDataGrid_Edit"
           OnCancelCommand="MyDataGrid_Cancel" 
           OnDeleteCommand="MyDataGrid_Delete"
           OnItemDataBound="MyDataGrid_ItemDataBound"
           >
         <HeaderStyle BackColor="Navy" 
                      ForeColor="White" 
                      Font-Bold="True" 
                      HorizontalAlign="Center"/>
         <PagerStyle Mode="NextPrev"
                     HorizontalAlign="Right" 
                     NextPageText="Next"
                     PrevPageText="Prev"/>
  <Columns>
         <asp:BoundColumn DataField="stuid" HeaderText="StuID" ReadOnly="true"/>
         <asp:BoundColumn DataField="stuname" HeaderText="stuname"/>
         <asp:TemplateColumn HeaderText="StuDepID">
                  <ItemTemplate>
                       <asp:Label ID="lblDepName" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "DepName") %>' />
                  </ItemTemplate>
                  <EditItemTemplate>
                        <asp:DropDownList id="dropDepName" DataSource="<%# BindDropDownList()%>" DataTextField="depName" DataTextValue="depID" runat="server" />
                  </EditItemTemplate>
             </asp:TemplateColumn>

        <asp:EditCommandColumn
            ButtonType="PushButton" UpdateText="Update" CancelText="Cancel"
            EditText="Edit" HeaderText="Edit">
        </asp:EditCommandColumn>

        <asp:TemplateColumn HeaderText="Delete">
             <ItemTemplate>
                <asp:Button CommandName="Delete" Text="Delete" ID="btnDel" Runat="server" />
             </ItemTemplate>
        </asp:TemplateColumn>
  </Columns>
</asp:DataGrid>
</form>