+++ 页面代码如下：
<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" DataKeyNames="username" DataSourceID="SqlDataSource1"
PageSize="3">
<Columns>
<asp:BoundField DataField="username" HeaderText="用户名" SortExpression="username" ReadOnly="true" />
<asp:BoundField DataField="userpwd" HeaderText="密码" SortExpression="userpwd" />
<asp:CommandField ShowEditButton="True"/>
<asp:CommandField ShowDeleteButton="True"/>
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="Data Source=ora9;User ID=scott;Password=tiger;Persist Security Info=True"
ProviderName="System.Data.OracleClient"
SelectCommand="SELECT USERNAME, USERPWD from USERS"
UpdateCommand="UPDATE USERS SET USERPWD =:userpwd where USERNAME = :username"
DeleteCommand="DELETE from USERS where USERNAME =:username">
<UpdateParameters>
<asp:ControlParameter ControlID="GridView1" DefaultValue="username" Name="username"
PropertyName="SelectedValue" />
<asp:ControlParameter ControlID="GridView1" DefaultValue="userpwd" Name="userpwd"
PropertyName="SelectedValue" />
</UpdateParameters>
<DeleteParameters>
<asp:ControlParameter ControlID="GridView1" Default
