BaseDataList.DataKeys 屬性
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
取得 DataKeyCollection 物件，其將每個資料錄的索引鍵值儲存在資料清單控制項中。
public:
property System::Web::UI::WebControls::DataKeyCollection ^ DataKeys { System::Web::UI::WebControls::DataKeyCollection ^ get(); };[System.ComponentModel.Browsable(false)]
public System.Web.UI.WebControls.DataKeyCollection DataKeys { get; }[<System.ComponentModel.Browsable(false)>]
member this.DataKeys : System.Web.UI.WebControls.DataKeyCollectionPublic ReadOnly Property DataKeys As DataKeyCollection屬性值
DataKeyCollection，將每個資料錄的索引鍵值儲存在資料清單控制項中。
- 屬性
範例
下列程式代碼範例示範如何使用 DataKeys 屬性來判斷所刪除記錄的索引鍵字段值。
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>BaseDataList DataKeys Example</title>
<script runat="server">
ICollection CreateDataSource()
{
// Create sample data for the DataGrid control.
DataTable dt = new DataTable();
DataRow dr;
// Define the columns of the table.
dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
// Define the primary key for the table as the IntegerValue
// column (column 0). To do this, first create an array of
// DataColumns to represent the primary key. The primary key can
// consist of multiple columns, but in this example, only
// one column is used.
DataColumn[] keys = new DataColumn[1];
keys[0] = dt.Columns[0];
// Then assign the array to the PrimaryKey property of the DataTable.
dt.PrimaryKey = keys;
// Populate the table with sample values.
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
// To persist the data source between posts to the server,
// store it in session state.
Session["Source"] = dt;
DataView dv = new DataView(dt);
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
// Load sample data only once, when the page is first loaded.
if (!IsPostBack)
{
ItemsGrid.DataSource = CreateDataSource();
ItemsGrid.DataBind();
}
}
void Delete_Command(Object sender, DataGridCommandEventArgs e)
{
// Retrieve the data table from session state.
DataTable dt = (DataTable)Session["Source"];
// Retrieve the data row to delete from the data table.
// Use the DataKeys property of the DataGrid control to get
// the primary key value of the selected row.
// Search the Rows collection of the data table for this value.
DataRow row;
row = dt.Rows.Find(ItemsGrid.DataKeys[e.Item.ItemIndex]);
// Delete the item selected in the DataGrid from the data source.
if(row != null)
{
dt.Rows.Remove(row);
}
// Save the data source.
Session["Source"] = dt;
// Create a DataView and bind it to the DataGrid control.
DataView dv = new DataView(dt);
ItemsGrid.DataSource = dv;
ItemsGrid.DataBind();
}
</script>
</head>
<body>
<form id="form1" runat="server">
<h3>BaseDataList DataKeys Example</h3>
<asp:DataGrid id="ItemsGrid"
BorderColor="Black"
ShowFooter="False"
CellPadding="3"
CellSpacing="0"
HeaderStyle-BackColor="#aaaadd"
DataKeyField="IntegerValue"
OnDeleteCommand="Delete_Command"
runat="server">
<Columns>
<asp:ButtonColumn Text="Delete"
CommandName="Delete"/>
</Columns>
</asp:DataGrid>
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>BaseDataList DataKeys and DataKeyField Example</title>
<script runat="server">
Function CreateDataSource() As ICollection
' Create sample data for the DataGrid control.
Dim dt As DataTable = New DataTable()
Dim dr As DataRow
' Define the columns of the table.
dt.Columns.Add(new DataColumn("IntegerValue", GetType(Integer)))
dt.Columns.Add(new DataColumn("StringValue", GetType(String)))
dt.Columns.Add(new DataColumn("CurrencyValue", GetType(Double)))
' Define the primary key for the table as the IntegerValue
' column (column 0). To do this, first create an array of
' DataColumns to represent the primary key. The primary key can
' consist of multiple columns, but in this example, only
' one column is used.
Dim keys(1) As DataColumn
keys(0) = dt.Columns(0)
' Then assign the array to the PrimaryKey property of the DataTable.
dt.PrimaryKey = keys
' Populate the table with sample values.
Dim i As Integer
For i = 0 To 8
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = 1.23 * (i + 1)
dt.Rows.Add(dr)
Next
' To persist the data source between posts to the server,
' store it in session state.
Session("Source") = dt
Dim dv As DataView = New DataView(dt)
Return dv
End Function
Sub Page_Load(sender As Object, e As EventArgs)
' Load sample data only once, when the page is first loaded.
If Not IsPostBack Then
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub
Sub Delete_Command(sender As Object, e As DataGridCommandEventArgs)
' Retrieve the data table from session state.
Dim dt As DataTable = CType(Session("Source"), DataTable)
' Retrieve the data row to delete from the data table.
' Use the DataKeys property of the DataGrid control to get
' the primary key value of the selected row.
' Search the Rows collection of the data table for this value.
Dim row As DataRow
row = dt.Rows.Find(ItemsGrid.DataKeys(e.Item.ItemIndex))
' Delete the item selected in the DataGrid from the data source.
If Not row is Nothing Then
dt.Rows.Remove(row)
End If
' Save the data source.
Session("Source") = dt
' Create a DataView and bind it to the DataGrid control.
Dim dv As DataView = New DataView(dt)
ItemsGrid.DataSource = dv
ItemsGrid.DataBind()
End Sub
</script>
</head>
<body>
<form id="form1" runat="server">
<h3>BaseDataList DataKeys and DataKeyField Example</h3>
<asp:DataGrid id="ItemsGrid"
BorderColor="Black"
ShowFooter="False"
CellPadding="3"
CellSpacing="0"
HeaderStyle-BackColor="#aaaadd"
DataKeyField="IntegerValue"
OnDeleteCommand="Delete_Command"
runat="server">
<Columns>
<asp:ButtonColumn Text="Delete"
CommandName="Delete"/>
</Columns>
</asp:DataGrid>
</form>
</body>
</html>
備註
DataKeys使用 集合來存取每個記錄的索引鍵值， (顯示在數據清單控件中的數據列) 。 這可讓您使用數據清單控制件來儲存索引鍵欄位，而不在控件中顯示它。 這個集合會自動填入 屬性所 DataKeyField 指定欄位的值。
索引鍵欄位通常用於事件的處理程式，例如 ItemCommand 或 DeleteCommand，做為更新查詢字串的一部分，以修改數據源中的特定記錄。 索引鍵欄位可協助更新查詢字串識別要修改的適當記錄。
如需使用 ASP.NET 存取數據的詳細資訊，請參閱 ASP.NET 數據存取內容對應。
