记录一下，主要是这句：
TextBox txtNum = e.Item.FindControl("txtNum") as TextBox;

Repeater真是太强了，太灵活。除了Repeater别的都不用。

<table>
    <asp:Repeater ID="rptList" runat="server" OnItemCommand="rptList_ItemCommand">
    <ItemTemplate>
<tr>
    <td><asp:TextBox ID="txtNum" runat="server" Text= <%#Eval("ProNum") %> ></asp:TextBox></td>
    <td><asp:Button ID="btn " runat="server" Text="更新" CommandName=" " CommandArgument= <%#Eval("PID") %> /></td>
</tr>
    </ItemTemplate>
    </asp:Repeater>
</table>

protected void rptList_ItemCommand(object source, RepeaterCommandEventArgs e)
{
    switch (e.CommandName)
     {
        case " ":
            string arg = e.CommandArgument.ToString();//取得参数
            //找到激发事件的行内控件，这个很有用，能将更多需要的参数值传递过来。
             TextBox txtNum = e.Item.FindControl("txtNum") as TextBox;
            
            //下面执行业务逻辑
            string jsStr = "< >alert( 删除成功!" + txtNum.Text + " )</ >";
             Page.Client .RegisterClient Block(this.GetType(), "alert", jsStr, false);
            break;
     }
     Bind();
}

protected void rptList_ItemCommand(object source, RepeaterCommandEventArgs e)
{
    switch (e.CommandName)
     {
        case " ":
            string arg = e.CommandArgument.ToString();//取得参数
            //找到激发事件的行内控件，这个很有用，能将更多需要的参数值传递过来。
             TextBox txtNum = e.Item.FindControl("txtNum") as TextBox;
            
            //下面执行业务逻辑
            string jsStr = "< >alert( 删除成功!" + txtNum.Text + " )</ >";
             Page.Client .RegisterClient Block(this.GetType(), "alert", jsStr, false);
            break;
     }
     Bind();
}