DataView 类

表示用于排序、筛选、搜索、编辑和导航的 DataTable 的可绑定数据的自定义视图。

**命名空间:**System.Data
**程序集:**System.Data（在 system.data.dll 中）

语法

声明
Public Class DataView
    Inherits MarshalByValueComponent
    Implements IBindingListView, IBindingList, IList, ICollection, _
    IEnumerable, ITypedList, ISupportInitializeNotification, ISupportInitialize
用法
Dim instance As DataView

public class DataView : MarshalByValueComponent, IBindingListView, IBindingList, IList, 
    ICollection, IEnumerable, ITypedList, ISupportInitializeNotification, ISupportInitialize

public ref class DataView : public MarshalByValueComponent, IBindingListView, IBindingList, IList, 
    ICollection, IEnumerable, ITypedList, ISupportInitializeNotification, ISupportInitialize

public class DataView extends MarshalByValueComponent implements IBindingListView, IBindingList, 
    IList, ICollection, IEnumerable, ITypedList, ISupportInitializeNotification, 
    ISupportInitialize

public class DataView extends MarshalByValueComponent implements IBindingListView, IBindingList, 
    IList, ICollection, IEnumerable, ITypedList, ISupportInitializeNotification, 
    ISupportInitialize

备注

DataView 的一个主要功能是允许在 Windows 窗体和 Web 窗体上进行数据绑定。

另外，可自定义 DataView 来表示 DataTable 中数据的子集。此功能让您拥有绑定到同一 DataTable、但显示不同数据版本的两个控件。例如，一个控件可能绑定到显示表中所有行的 DataView，而另一个控件可能配置为只显示已从 DataTable 删除的行。DataTable 也具有 DefaultView 属性。它返回表的默认 DataView。例如，如果希望在表上创建自定义视图，请在 DefaultView 返回的 DataView 上设置 RowFilter。

若要创建数据的筛选和排序视图，请设置 RowFilter 和 Sort 属性。然后，使用 Item 属性返回单个 DataRowView。

还可使用 AddNew 和 Delete 方法从行的集合中进行添加和删除。在使用这些方法时，可设置 RowStateFilter 属性以便指定只有已被删除的行或新行才可由 DataView 显示。

示例

下面的示例创建一个具有一个列和五个行的 DataTable。创建两个 DataView 对象，并针对每个对象设置 RowStateFilter 以显示表数据的不同视图。然后打印这些值。

Private Sub DemonstrateDataView()
    ' Create one DataTable with one column.
    Dim table As DataTable = New DataTable("table")
    Dim colItem As DataColumn = New DataColumn("item", _
        Type.GetType("System.String"))
    table.Columns.Add(colItem)

    ' Add five items.
    Dim NewRow As DataRow
    Dim i As Integer
    For i = 0 To 4
    
    NewRow = table.NewRow()
    NewRow("item") = "Item " & i
    table.Rows.Add(NewRow)
    Next
    table.AcceptChanges()

    ' Create two DataView objects with the same table.
    Dim firstView As DataView = New DataView(table)
    Dim secondView As DataView = New DataView(table)
    
    ' Change the values in the table.
    table.Rows(0)("item") = "cat"
    table.Rows(1)("item") = "dog"
    
    ' Print current table values.
    PrintTableOrView(table, "Current Values in Table")
        
    ' Set first DataView to show only modified versions of original rows.
    firstView.RowStateFilter = DataViewRowState.ModifiedOriginal

    ' Print values.    
    PrintTableOrView(firstView, "First DataView: ModifiedOriginal")

    ' Add one New row to the second view.
    Dim rowView As DataRowView
    rowView = secondView.AddNew()
    rowView("item") = "fish"
    ' Set second DataView to show modified versions of 
    ' current rows, or New rows.
    secondView.RowStateFilter = DataViewRowState.ModifiedCurrent _
        Or DataViewRowState.Added
    ' Print modified and Added rows.
    PrintTableOrView(secondView, _
        "Second DataView: ModifiedCurrent or Added")
End Sub
    
Overloads Private Sub PrintTableOrView( _
    ByVal view As DataView, ByVal label As String)
    Console.WriteLine(label)
    Dim i As Integer
    For i = 0 To view.count - 1
    
    Console.WriteLine(view(i)("item"))
    Next
    Console.WriteLine()
End Sub
    
Overloads Private Sub PrintTableOrView( _
    ByVal table As DataTable, ByVal label As String)
    Console.WriteLine(label)
    Dim i As Integer
    For i = 0 To table.Rows.Count - 1
    Console.WriteLine(table.Rows(i)("item"))
    Next
    Console.WriteLine()
End Sub

private void DemonstrateDataView()
{
    // Create one DataTable with one column.
    DataTable table = new DataTable("table");
    DataColumn colItem = new DataColumn("item",
        Type.GetType("System.String"));
    table.Columns.Add(colItem);

    // Add five items.
    DataRow NewRow;
    for(int i = 0; i <5; i++)
    {
        NewRow = table.NewRow();
        NewRow["item"] = "Item " + i;
        table.Rows.Add(NewRow);
    }
    // Change the values in the table.
    table.Rows[0]["item"]="cat";
    table.Rows[1]["item"] = "dog";
    table.AcceptChanges();
 
    // Create two DataView objects with the same table.
    DataView firstView = new DataView(table);
    DataView secondView = new DataView(table);
 
    // Print current table values.
    PrintTableOrView(table,"Current Values in Table");

    // Set first DataView to show only modified 
    // versions of original rows.
    firstView.RowStateFilter=DataViewRowState.ModifiedOriginal;

    // Print values.   
    PrintTableOrView(firstView,"First DataView: ModifiedOriginal");

    // Add one New row to the second view.
    DataRowView rowView;
    rowView=secondView.AddNew();
    rowView["item"] = "fish";

    // Set second DataView to show modified versions of 
    // current rows, or New rows.
    secondView.RowStateFilter=DataViewRowState.ModifiedCurrent 
        | DataViewRowState.Added;
    // Print modified and Added rows.
    PrintTableOrView(secondView, 
        "Second DataView: ModifiedCurrent | Added");
}
 
private void PrintTableOrView(DataTable table, string label)
{
    // This function prints values in the table or DataView.
    Console.WriteLine("\n" + label);
    for(int i = 0; i<table.Rows.Count;i++)
    {
        Console.WriteLine("\table" + table.Rows[i]["item"]);
    }
    Console.WriteLine();
}
 
private void PrintTableOrView(DataView view, string label)
{
 
    // This overload prints values in the table or DataView.
    Console.WriteLine("\n" + label);
    for(int i = 0; i<view.Count;i++)
    {
        Console.WriteLine("\table" + view[i]["item"]);
    }
    Console.WriteLine();
}

继承层次结构

System.Object
   System.ComponentModel.MarshalByValueComponent
    System.Data.DataView

线程安全

该类型对于多线程读操作是安全的。您必须使任何写操作同步。

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

.NET Compact Framework

受以下版本支持：2.0、1.0

请参见

参考

DataView 成员
System.Data 命名空间
DataSet 类
DataTable 类
DataViewManager