DataList教程
DataList<spanstyle='font-size:14.0pt;mso-bidi-font-size:10.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"'>控件的使用<spanlang=EN-US style='font-size:14.0pt;mso-bidi-font-size:10.0pt'>
<bstyle='mso-bidi-font-weight:normal'>使用<bstyle='mso-bidi-font-weight:normal'>DataList<bstyle='mso-bidi-font-weight:normal'>控件<bstyle='mso-bidi-font-weight:normal'><spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
本章内容：
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 1、理解事件冒泡<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 2、使用模板<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 3、在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中显示数据
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 4、在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中创建多列
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 5、捕获<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件中产生的事件
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 6、选择<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中的项
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 7、使用<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件中的DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 8、编辑<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中的项
本章介绍在ASP.NET<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>框架中功能最强大的两个控件（DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件和DataGrid<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件）之一的DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件。我们将深入探讨DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件，学习如何使用该控件显示数据以及编辑数据库数据。
一、理解事件冒泡
在ASP.NET框架包含三个支持事件冒泡的标准控件：<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>Repeater、DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>和DataGrid<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件。这些控件可以让你捕获其子控件的时间。当子控件产生一个事件时，事件就“<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>冒泡”传给包含该子控件的容器控件，并且容器控件就可以执行一个子程序来处理该事件。<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
二、使用模板
在前一章中我们已经介绍过<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>Repeater控件的五个模板（ItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、AlternationgItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、SeparatorTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、HeaderTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、FooterTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>），可以格式化控件的输出。在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件中除了支持Repeater<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件中的五个模板以外，还支持如下两个模板：
1、SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>：控制如何格式化被选定的项
2、EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>：控制如何格式化被编辑的项。
当选定DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中选中一个项时（即DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的SelectedIndex<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性值为当前选定项的索引值），将显示SelectedItem<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板，当在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中选择一个项来编辑（即DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的EditItemIndex<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性值为当前选定项的索引值）时，将显示EditItem<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板。
三、在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中显示数据：
可以像<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>Repeater控件那样来用DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>显示数据库表中的记录。但是，与Repeater<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件不同的是：DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的默认行为是在HTML<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>表格中显示数据库记录。
如下程序清单演示如何显示pubs数据库中<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>authors表中的数据。
<%@ Page Language="C#"%>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat=server>
void Page_Load(Object sender , EventArgs e)
{
SqlConnection conn;
SqlCommand cmd;
SqlDataReader dr;
conn = new SqlConnection( "Server=localhost;Database=Pubs;uid=cdd;psw=123" );
cmd = new SqlCommand( "Select au_fname From authors", conn );
conn.Open();
dr = cmdSelect.ExecuteReader();
DataList1.DataSource = dr;
DataList1.DataBind();
dr.Close();
conn.Close();
}
</Script>
<html>
<head><title>DataList.aspx</title></head>
<body>
<form Runat="Server">
<asp:DataList
ID="DataList1"
Runat="Server">
<ItemTemplate>
<%#DataBinder.Eval(Container.DataItem, "au_fname" )%>
</ItemTemplate>
</asp:DataList>
</form>
</body>
</html>
在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中显示记录时，authors<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>表中每行都显示在独立的HTML<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>表格中，只要你愿意，也可以修改其RepeatLayout<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性把DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的项显示在HTML<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的<div></div><spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中。在默认情况下，<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:red'>RepeatLayout属性值为Table<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>。如果把<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>RepeatLayout属性设为Flow<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，那么每个项就显示在<div></div><spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中。
<asp:DataList RepeatLayout=”Flow<spanlang=EN-US style='mso-ascii-font-family:Verdana;color:black'>”<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> Runat=”Server<spanlang=EN-US style='mso-ascii-font-family:Verdana;color:black'>”<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>>
当RepeatLayout<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性为Table<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>时，通过设置GridLines<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性可以在每个单元格周围显示线条。GridLines<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性可选值有： Both / Horizontal /Vertical
四、在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中创建多列
DataList的一个好处的特征是可以以多个列显示数据现。通过设置其<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>RepeatColumns和RepeatDirection<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性，可以控制DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的列的布局。
RepeatColumns属性决定要显示的列的数量。比如，如果要在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中显示四列的项，那么可以把这个属性设为4<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>。
RepeatDirection属性句顶列是按水平或垂直方向来重复。在默认情况下，<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>RepeatDirection值为Vertical<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，因此，如果RepeatColumns<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>值为4<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，则列就像这样显示：
Column 1 Column3 Column5 Column7
Column 2 Column4 Column6 Column8
如果把RepeatDirection<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>设为Horizontal<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，而且RepeatColumns<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>值为4<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，那么列就像这样显示：
Column 1 Column3 Column5 Column7
Column 2 Column4 Column6 Column8
注意，即使RepeatDirection<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>值为Vertical<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，还是显示为4<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>个列。RepeatColumns<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>永远是指重复的列的数量，而不是行的数量。
五、捕获DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件中产生的事件
正如第一小节中提到的那样，<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件支持事件冒泡，可以捕获DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>内包含的控件产生的事件，并且通过普通的子程序处理这些事件。讲到这里有些人可能不太明白事件冒泡的好处所在，这样，我们反过来思考：如果没有事件冒泡，那么对于<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList内包含的每一个控件产生的事件都需要定义一个相应的处理函数，如果DataList中包含<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>10000个控件呢？或者更多呢？那我们得写多少个事件处理程序。所以有了事件冒泡，不管DataList中包含多少个控件，我们只需要一个处理程序就可以了。<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件支持五个事件：
1) EditCommand：由带有<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>CommandName=”edit”的子控件产生<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
2) CancelCommand：由带有<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>CommandName=”cancel”的子控件产生<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
3) UpdateCommand：由带有<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>CommandName=”update”的子控件产生<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
4) DeleteCommand：由带有<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>CommandName=”delete”的子控件产生<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
5) ItemCommand：DataList的默认事件<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
有了这五个事件，那么当我点击了DataList控件中的某一个按钮的时候，应该触发哪一个事件呢？什么时候才触发它们呢？在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ASP.NET中有三个控件带有CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性，分别是Button<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>和ImageButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，可以设置它们的CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性来表示容器控件内产生的时间类型。比如，如果设置DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的一个LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性为“update<spanlang=EN-US style='mso-ascii-font-family:Verdana;color:black'>”<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，那么点击此按钮的时候，将会触发DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的CancelCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，我们可以将相关处理代码写到对应的事件处理程序中去。
如下程序清单演示了点击<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中三个CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>分别为edit<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、delete<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>、update<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>按钮。当点击不同的按钮时，在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中产生不同的事件，执行不同的程序：
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat=server>
void Page_Load(Object sender , EventArgs e)
{
if (! IsPostBack ) {
SqlConnection conn;
SqlCommand cmd;
SqlDataReader dr;
conn = new SqlConnection( "Server=localhost;Database=Pubs;uid=cdd;psw=123" );
cmd = new SqlCommand( "Select au_fname From authors", conn );
conn.Open();
dr = cmd.ExecuteReader();
dlstTitles.DataSource = dr;
dlstTitles.DataBind();
dr.Close();
conn.Close();
}
}
void DataList1_ItemCommand( object s, DataListCommandEventArgs e ) {
lblMessage.Text = "<li>Item Command!";
}
void DataList1_EditCommand( object s, DataListCommandEventArgs e ) {
lblMessage.Text += "<li>Editing Item!";
}
void DataList1_DeleteCommand( object s, DataListCommandEventArgs e ) {
lblMessage.Text = "<li>Deleting Item!";
}
void DataList1_UpdateCommand( object s, DataListCommandEventArgs e ) {
lblMessage.Text = "<li>Updating Item!";
}
</Script>
<html>
<head><title>DataListEvents.aspx</title></head>
<body>
<form Runat="Server">
<asp:Label
ID="lblMessage"
BackColor="yellow"
Runat="Server" />
<p>
<asp:DataList
ID="DataList1"
OnItemCommand="DataList1_ItemCommand"
OnEditCommand="DataList1_EditCommand"
OnDeleteCommand="DataList1_DeleteCommand"
OnUpdateCommand="DataList1_UpdateCommand"
GridLines="Both"
CellPadding="4"
Runat="Server">
<ItemTemplate>
<%#DataBinder.Eval(Container.DataItem, " au_fname " )%>
<br>
<asp:LinkButton
Text="Edit!"
CommandName="edit"
Runat="Server"/>
<asp:LinkButton
Text="Delete!"
CommandName="delete"
Runat="Server"/>
<asp:LinkButton
Text="Update!"
CommandName="update"
Runat="Server"/>
</ItemTemplate>
</asp:DataList>
</form>
</body>
</html>
在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中显示的三个LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件分别与相应的程序相关联。当点击名为delete<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的时候，就触发DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件DeleteCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，该事件与DataList1_DeleteCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>函数相关联。
大家注意到与<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList关联的函数都带有一个DataListCommandEventArgs<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的参数。该阐述表示从DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>传递给该函数的信息。DataListCommandEventArgs<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>具有如下属性：
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> CommandArgument：表示来自于产生该事件的控件的CommandArgument<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性值。
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> CommandName：表示产生该事件的命令名称。
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> CommandSource：表示产生该事件的DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件。
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> Item<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>：表示来自DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>的项。就是DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>中发生事件的那一项。该属性非常有用，在后面的章节中会经常使用到！<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
六、选择DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的项
在第一小节中我们讲到<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件比Repeater<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件多两个模板，SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板可以格式化DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中被选定的项的格式。
数据绑定到<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList后，DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的每一项都有一个索引号，第一项的索引为0<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，依次往下编号。我们可以利用索引来确定DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中具体的项。
DataList默认以<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ItemTemplate或ItemTemplate+AlternatingItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板显示数据项，当DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的SelectedIndex<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性（该属性默认值为-1<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，表示不显示SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板）的值为DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>某一项的索引的时候，对应的项将会以SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板显示。
如下程序清单使用DataList来显示一列来自于<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>Authors数据库表中的作者的姓。每个作者的姓作为一个LinkButton<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件呈现。当选择一个作者时，被选定的作者就使用SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>来显示。
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat=server>
void Page_Load(Object sender , EventArgs e)
{
if (! IsPostBack)
{
BindDataList();
}
}
void BindDataList() {
SqlConnection conn;
SqlCommand cmd;
SqlDataReader dr;
conn = new SqlConnection("Server=localhost;Database=Pubs;uid=cdd;psw=123" );
cmd = new SqlCommand( "Select au_lname From Authors", conn );
conn.Open();
dr = cmd.ExecuteReader();
dlstAuthors.DataSource = dr;
dlstAuthors.DataBind();
dr.Close();
conn.Close();
}
void DataList1_ItemCommand( object s, DataListCommandEventArgs e ) {
dlstAuthors.SelectedIndex = e.Item.ItemIndex;
BindDataList();
}
</Script>
<html>
<head><title>DataListSelected.aspx</title></head>
<body>
<form Runat="Server">
<asp:DataList
ID=" DataList1"
OnItemCommand=" DataList1_ItemCommand"
Runat="Server">
<ItemTemplate>
<asp:LinkButton
Text='<%#DataBinder.Eval(Container.DataItem, "au_lname" )%>'
Runat="Server" />
</ItemTemplate>
<SelectedItemTemplate>
<b><i><%#DataBinder.Eval(Container.DataItem,"au_lname" )%></i></b>
</SelectedItemTemplate>
</asp:DataList>
</form>
</body>
</html>
上面代码中DataList1.SelectedIndex= e.Item.ItemIndex语句：表示把被选项的索引赋值给<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件的SelectedIndex<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性。然后调用BindDataList()<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>进行数据的重新绑定。
答疑：<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>在一次课上，讲解ItemCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件和DeleteCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件的时候，有学生问我为什么每次点了CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>为“delete<spanlang=EN-US style='mso-ascii-font-family:Verdana;color:black'>”<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的按钮的时候ItemCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件也被触发了呢？因为我平时写程序的时候没注意这个问题，一下子还真把我难住了！<spanstyle='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 回办公室后反复做了实验（通过打开页面的<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>Trace跟踪，在相应的事件里用Trace.Warn()<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>方法输出），最后得出结论：
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> ItemCommand事件是DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件产生的默认事件，任何DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件中CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>为delete/cancel/update/edit<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的按钮被点击后，首先触发的是ItemCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，然后才是相应的事件。
Ø<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 但是当<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件中存在一个普通按钮，点击后触发ItemCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，假设执行功能为选择当前项，此时如果点击了CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>为edit<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的按钮，将当前项显示为编辑状态。这个时候并没有出现当前行既被选中又被编辑的情形，这和以上的结论（先触发<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ItemCommand事件）好象相违背。事实上这并不矛盾，因为DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件中的项同一时刻只能显示一个EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>或SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板，所以执行过程应该是这样的。点击了CommandName<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>为edit<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的按钮后首先触发了ItemCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，将当前的项显示为SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板，然后再触发EditCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，将当前的项显示为EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板，覆盖了前面已经显示的SelectedItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板，只不过因为速度太快，肉眼看不出这个过程而已！
七、使用<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件中的DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合
在选择<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中的一个项时，通常需要获取与这个项相关联的主键的值。可以使用DataKeys集合来获取与一个项想关联的主键的值。<spanstyle='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
假设要在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中显示一个名为Authors<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的数据库表，其中包含两个名为au_id<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>和au_fname<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的列，当拥护选择DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的一个项时，你要提取与被选项相关联的au_id<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>列的值，要实现这个操作，则需要设置DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的DataKeyField<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性：
<asp:DataList
ID="DataList1"
DataKeyField="au_id"
OnItemCommand="DataList1_ItemCommand"
Runat="Server">
如果把数据库表的主键类的名称赋值给<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataKeyField属性，那么当绑定DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>到Authors<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的数据表时，一个名为DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的特殊集合就自动生成了。DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合包含来自数据库表的所以的主键值，起顺序与DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的项相同。
注意：只有当所使用的数据表具有单个主键列时，才可以使用<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:red'>DataKeys集合。也就是说不能使用联合主键。
在创建了<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataKeys集合后，就可以通过传递项的索引值给DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合来获取DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中与相关项关联的主键值。比如，要获取由DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>显示的第三项的主键值，就可以是使用语句：DataList1.DataKeys[2]// DataList1为DataList控件的<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ID值<spanstyle='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
如果要在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList控件的事件处理函数中发生事件的项的主键值，则可以使用语句：DataList1.DataKeys[e.Item.ItemIndex] // DataList1<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>为DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的ID<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>值
八、编辑<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList中的项★★★★★
可以使用DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件来编辑数据表中的某一条记录，如下图，事实上，在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中完成这样的操作非常的方便，不像在asp<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中需要在多个页面中来回切换。
DataList控件具有一个名为<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>EditItemTemplate的模板，可以在EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中放置表单控件，以便能在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中编辑特定的项。当DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的EditItemIndex<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性（该属性默认值为-1<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，表示不显示EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板）的值为DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>某一项的索引的时候，对应的项将会以EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板显示。
注意：在DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>中一次只能有一个项被选定来编辑。
如下程序清单演示了如何编辑DataList的项，其中最主要的部分就是<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>UpdateCommand事件的处理程序，因为DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>并不会替你处理更新数据表的操作，你必须自己编写所有的代码：
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat=server>
void Page_Load(Object sender , EventArgs e)
{
if (! IsPostBack ) {
BindDataList();
}
}
void BindDataList() {
SqlConnection conn;
SqlCommand cmd;
SqlDataReader dr;
conn = new SqlConnection("Server=localhost;Database=Pubs;uid=cdd;psw=123" );
cmd = new SqlCommand( "Select au_id, au_lname, phone From Authors Order byau_lname", conn );
conn.Open();
dr = cmd.ExecuteReader();
DataList1.DataSource = dr;
DataList1.DataBind();
dr.Close();
conn.Close();
}
void DataList1_EditCommand( object s, DataListCommandEventArgs e ) {
DataList1.EditItemIndex = e.Item.ItemIndex;
BindDataList();
}
void DataList1_CancelCommand( object s, DataListCommandEventArgs e ) {
DataList1.EditItemIndex = -1;
BindDataList();
}
void DataList1_DeleteCommand( object s, DataListCommandEventArgs e ) {
SqlConnection conn;
string strDelete;
SqlCommand cmdDelete;
string strAuthorID;
strAuthorID = DataList1.DataKeys[(int)e.Item.ItemIndex].ToString();
conn = new SqlConnection("Server=localhost;Database=Pubs;uid=cdd;psw=123" );
strDelete = "Delete Authors Where au_id=@authorID";
cmdDelete = new SqlCommand( strDelete, conn );
cmdDelete.Parameters.Add( "@authorID", strAuthorID );
conn.Open();
cmdDelete.ExecuteNonQuery();
conn.Close();
DataList1.EditItemIndex = -1;
BindDataList();
}
void DataList1_UpdateCommand( object s, DataListCommandEventArgs e ) {
SqlConnection conn;
string strUpdate;
SqlCommand cmdUpdate;
string strAuthorID;
strAuthorID = DataList1.DataKeys[(int)e.Item.ItemIndex].ToString();
TextBox txtLastName = (TextBox)e.Item.FindControl( "txtLastName" );
TextBox txtPhone = (TextBox)e.Item.FindControl( "txtPhone" );
conn = new SqlConnection("Server=localhost;Database=Pubs;uid=cdd;psw=123" );
strUpdate = "Update Authors set au_lname=@lastname, phone=@phone Whereau_id=@authorID";
cmdUpdate = new SqlCommand( strUpdate, conn );
cmdUpdate.Parameters.Add( "@authorID", strAuthorID );
cmdUpdate.Parameters.Add( "@lastname", txtLastName.Text );
cmdUpdate.Parameters.Add( "@phone", txtPhone.Text );
conn.Open();
cmdUpdate.ExecuteNonQuery();
conn.Close();
DataList1.EditItemIndex = -1;
BindDataList();
}
</Script>
<html>
<head><title>DataListEdit.aspx</title></head>
<body>
<form Runat="Server">
<asp:DataList
ID="DataList1"
DataKeyField="au_id"
OnEditCommand="DataList1_EditCommand"
OnCancelCommand="DataList1_CancelCommand"
OnDeleteCommand="DataList1_DeleteCommand"
OnUpdateCommand="DataList1_UpdateCommand"
RepeatColumns="4"
GridLines="Both"
CellPadding="10"
EditItemStyle-BackColor="lightgrey"
Runat="Server">
<ItemTemplate>
<%#DataBinder.Eval(Container.DataItem, "au_lname" )%>
- <%#DataBinder.Eval(Container.DataItem, "phone" )%>
<br>
<asp:LinkButton
Text="Edit!"
CommandName="edit"
Runat="Server" />
</ItemTemplate>
<EditItemTemplate>
<b>Last Name:</b>
<br>
<asp:TextBox
ID="txtLastName"
Text='<%#DataBinder.Eval(Container.DataItem, "au_lname" )%>'
Runat="Server" />
<p>
<b>Phone:</b>
<br>
<asp:TextBox
ID="txtPhone"
Text='<%#DataBinder.Eval(Container.DataItem, "phone" )%>'
Runat="Server" />
<p>
<asp:LinkButton
Text="Update!"
CommandName="update"
Runat="Server" />
<asp:LinkButton
Text="Delete!"
CommandName="delete"
Runat="Server" />
<asp:LinkButton
Text="Cancel!"
CommandName="cancel"
Runat="Server" />
</EditItemTemplate>
</asp:DataList>
</form>
</body>
</html>
运行以上程序，点击其中某一项中的<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>edit按钮的时候，将触发DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的EditCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，通过执行语句DataList1.EditItemIndex =e.Item.ItemIndex;将当前项显示为<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>EditItemTemplate模板，在EditItemTemplate<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>模板中点击cancel<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>按钮的时候，将触发DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的CancelCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，通过执行语句DataList1.EditItemIndex =-1; 将当前项恢复显示为<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ItemTemplate模板；
当点击<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>update按钮的时候，将触发DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的UpdateCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件，在UpdateCommand<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>事件的处理程序中，我们需要取得当前项对应的主键值及修改之后的值才能够完成更新，通过执行语句<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>DataList1.DataKeys[(int)e.Item.ItemIndex].ToString();<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>来获取当前主键值（前提是指定了DataList1<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>的DataKeyField<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>属性值为主键字段），由于DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合返回数据类型为object<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>类型，我们还需要调用其ToString()<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>方法来转换成字符串类型。通过执行语句(TextBox)e.Item.FindControl("txtLastName" )来获得更新后的<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>au_lname的值，FindControl<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>（”控件ID”）方法通过检索当前项中包含的特定<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:red'>ID的控件，其返回值类型为<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:red'>Control类型，所以还需要强制将其转换为TextBox<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>类型，如果没有找到该ID<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:red'>的控件，则返回0<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，最后通过取得的主键值和更新后的字段的值更新数据库表。最后不要忘了重新绑定一下，否则数据库里最新的数据将不会显示出来。<spanstyle='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>
（<spanstyle='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'> 如果要在更新前对更新后的数据进行验证，则可以在<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>EditItemTemplate模板中加入验证控件进行验证。）
本章我们讨论了<spanlang=EN-US style='font-family:"Verdana","sans-serif";mso-hansi-font-family:"Times New Roman";color:black'>ASP.NET框架中包含的两个功能最强大的控件之一DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>，主要学习了一些公共属性、时间冒泡、模板和DataKeys<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>集合。其中最主要的是如何编辑DataList<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>中的项，再以后我们学习DataGrid<spanstyle='font-family:宋体;mso-ascii-font-family:Verdana;mso-hansi-font-family:"Times New Roman";color:black'>控件的时候，我们还会接触一些高级特性，如分页、排序等。<spanstyle='mso-spacerun:yes'>
