DataTable 类

项目
08/17/2007

表示内存中数据的一个表。

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

语法

声明
<SerializableAttribute> _
Public Class DataTable
    Inherits MarshalByValueComponent
    Implements IListSource, ISupportInitializeNotification, ISupportInitialize, ISerializable, _
    IXmlSerializable
用法
Dim instance As DataTable

[SerializableAttribute] 
public class DataTable : MarshalByValueComponent, IListSource, ISupportInitializeNotification, ISupportInitialize, 
    ISerializable, IXmlSerializable

[SerializableAttribute] 
public ref class DataTable : public MarshalByValueComponent, IListSource, ISupportInitializeNotification, ISupportInitialize, 
    ISerializable, IXmlSerializable

/** @attribute SerializableAttribute() */ 
public class DataTable extends MarshalByValueComponent implements IListSource, ISupportInitializeNotification, 
    ISupportInitialize, ISerializable, IXmlSerializable

SerializableAttribute 
public class DataTable extends MarshalByValueComponent implements IListSource, ISupportInitializeNotification, 
    ISupportInitialize, ISerializable, IXmlSerializable

备注

DataTable 是 ADO.NET 库中的核心对象。其他使用 DataTable 的对象包括 DataSet 和 DataView。

当访问 DataTable 对象时，请注意它们是按条件区分大小写的。例如，如果一个 DataTable 被命名为“mydatatable”，另一个被命名为“Mydatatable”，则用于搜索其中一个表的字符串被认为是区分大小写的。但是，如果“mydatatable”存在而“Mydatatable”不存在，则认为该搜索字符串不区分大小写。一个 DataSet 可以包含两个 DataTable 对象，它们具有相同的 TableName 属性值和不同的 Namespace 属性值。有关使用 DataTable 对象的更多信息，请参见创建 DataTable。

如果正在以编程方式创建 DataTable，则必须先通过将 DataColumn 对象添加到 DataColumnCollection（通过 Columns 属性访问）中来定义其架构。有关添加 DataColumn 对象的更多信息，请参见在表中添加列。

若要向 DataTable 中添加行，必须先使用 NewRow 方法返回新的 DataRow 对象。NewRow 方法返回具有 DataTable 的架构的行，就像由该表的 DataColumnCollection 定义的那样。DataTable 可存储的最大行数是 16,777,216。有关更多信息，请参见将数据添加到表中。

DataTable 也包含可用于确保数据完整性的 Constraint 对象的集合。有关更多信息，请参见将约束添加到表。

有许多 DataTable 事件可用于确定更改表的时间，其中包括：RowChanged、RowChanging、RowDeleting 和 RowDeleted。有关可与 DataTable 一起使用的事件的更多信息，请参见使用 DataTable 事件。

当创建 DataTable 的实例时，某些读/写属性将被设置为初始值。有关这些值的列表，请参见 System.Data.DataTable 构造函数主题。

提示

DataSet 和 DataTable 对象从 MarshalByValueComponent 继承，并支持用于 .NET Framework 远程处理的 ISerializable 接口。它们是唯一可用于 .NET Framework 远程处理的 ADO.NET 对象。

主题	位置
如何：创建数据表	Visual Studio 中的数据访问
如何：创建数据表	Visual Studio 中的数据访问

示例

下面的示例创建两个 DataTable 对象和一个 DataRelation 对象，并将这些新对象添加到 DataSet 中。这些表随后会显示在 DataGridView 控件中。

' Put the next line into the Declarations section.
private dataSet As DataSet 
 
Private Sub MakeDataTables()
    ' Run all of the functions. 
    MakeParentTable()
    MakeChildTable()
    MakeDataRelation()
    BindToDataGrid()
End Sub
 
Private Sub MakeParentTable()
    ' Create a new DataTable.
    Dim table As DataTable = new DataTable("ParentTable")

    ' Declare variables for DataColumn and DataRow objects.
    Dim column As DataColumn 
    Dim row As DataRow 
 
    ' Create new DataColumn, set DataType, ColumnName 
    ' and add to DataTable.    
    column = New DataColumn()
    column.DataType = System.Type.GetType("System.Int32")
    column.ColumnName = "id"
    column.ReadOnly = True
    column.Unique = True

    ' Add the Column to the DataColumnCollection.
    table.Columns.Add(column)
 
    ' Create second column.
    column = New DataColumn()
    column.DataType = System.Type.GetType("System.String")
    column.ColumnName = "ParentItem"
    column.AutoIncrement = False
    column.Caption = "ParentItem"
    column.ReadOnly = False
    column.Unique = False

    ' Add the column to the table.
    table.Columns.Add(column)
 
    ' Make the ID column the primary key column.
    Dim PrimaryKeyColumns(0) As DataColumn
    PrimaryKeyColumns(0)= table.Columns("id")
    table.PrimaryKey = PrimaryKeyColumns
 
    ' Instantiate the DataSet variable.
    dataSet = New DataSet()

    ' Add the new DataTable to the DataSet.
    dataSet.Tables.Add(table)
 
    ' Create three new DataRow objects and add 
    ' them to the DataTable
    Dim i As Integer
    For i = 0 to 2
       row = table.NewRow()
       row("id") = i
       row("ParentItem") = "ParentItem " + i.ToString()
       table.Rows.Add(row)
    Next i
End Sub
 
Private Sub MakeChildTable()
    ' Create a new DataTable.
    Dim table As DataTable = New DataTable("childTable")
    Dim column As DataColumn 
    Dim row As DataRow 
 
    ' Create first column and add to the DataTable.
    column = New DataColumn()
    column.DataType= System.Type.GetType("System.Int32")
    column.ColumnName = "ChildID"
    column.AutoIncrement = True
    column.Caption = "ID"
    column.ReadOnly = True
    column.Unique = True

    ' Add the column to the DataColumnCollection.
    table.Columns.Add(column)
 
    ' Create second column.
    column = New DataColumn()
    column.DataType= System.Type.GetType("System.String")
    column.ColumnName = "ChildItem"
    column.AutoIncrement = False
    column.Caption = "ChildItem"
    column.ReadOnly = False
    column.Unique = False
    table.Columns.Add(column)
 
    ' Create third column.
    column = New DataColumn()
    column.DataType= System.Type.GetType("System.Int32")
    column.ColumnName = "ParentID"
    column.AutoIncrement = False
    column.Caption = "ParentID"
    column.ReadOnly = False
    column.Unique = False
    table.Columns.Add(column)
 
    dataSet.Tables.Add(table)

    ' Create three sets of DataRow objects, five rows each, 
    ' and add to DataTable.
    Dim i As Integer
    For i = 0 to 4
       row = table.NewRow()
       row("childID") = i
       row("ChildItem") = "Item " + i.ToString()
       row("ParentID") = 0 
       table.Rows.Add(row)
    Next i
    For i = 0 to 4
       row = table.NewRow()
       row("childID") = i + 5
       row("ChildItem") = "Item " + i.ToString()
       row("ParentID") = 1 
       table.Rows.Add(row)
    Next i
    For i = 0 to 4
       row = table.NewRow()
       row("childID") = i + 10
       row("ChildItem") = "Item " + i.ToString()
       row("ParentID") = 2 
       table.Rows.Add(row)
    Next i
End Sub
 
Private Sub MakeDataRelation()
    ' DataRelation requires two DataColumn 
    ' (parent and child) and a name.
    Dim parentColumn As DataColumn = _
        dataSet.Tables("ParentTable").Columns("id")
    Dim childColumn As DataColumn = _
        dataSet.Tables("ChildTable").Columns("ParentID")
    Dim relation As DataRelation = new _
        DataRelation("parent2Child", parentColumn, childColumn)
    dataSet.Tables("ChildTable").ParentRelations.Add(relation)
End Sub
 
Private Sub BindToDataGrid()
    ' Instruct the DataGrid to bind to the DataSet, with the 
    ' ParentTable as the topmost DataTable.
    DataGrid1.SetDataBinding(dataSet,"ParentTable")
End Sub

// Put the next line into the Declarations section.
private System.Data.DataSet dataSet;
 
private void MakeDataTables()
{
    // Run all of the functions. 
    MakeParentTable();
    MakeChildTable();
    MakeDataRelation();
    BindToDataGrid();
}
 
private void MakeParentTable()
{
    // Create a new DataTable.
    System.Data.DataTable table = new DataTable("ParentTable");
    // Declare variables for DataColumn and DataRow objects.
    DataColumn column;
    DataRow row;
 
    // Create new DataColumn, set DataType, 
    // ColumnName and add to DataTable.    
    column = new DataColumn();
    column.DataType = System.Type.GetType("System.Int32");
    column.ColumnName = "id";
    column.ReadOnly = true;
    column.Unique = true;
    // Add the Column to the DataColumnCollection.
    table.Columns.Add(column);
 
    // Create second column.
    column = new DataColumn();
    column.DataType = System.Type.GetType("System.String");
    column.ColumnName = "ParentItem";
    column.AutoIncrement = false;
    column.Caption = "ParentItem";
    column.ReadOnly = false;
    column.Unique = false;
    // Add the column to the table.
    table.Columns.Add(column);
 
    // Make the ID column the primary key column.
    DataColumn[] PrimaryKeyColumns = new DataColumn[1];
    PrimaryKeyColumns[0] = table.Columns["id"];
    table.PrimaryKey = PrimaryKeyColumns;
 
    // Instantiate the DataSet variable.
    dataSet = new DataSet();
    // Add the new DataTable to the DataSet.
    dataSet.Tables.Add(table);
 
    // Create three new DataRow objects and add 
    // them to the DataTable
    for (int i = 0; i<= 2; i++)
    {
        row = table.NewRow();
        row["id"] = i;
        row["ParentItem"] = "ParentItem " + i;
        table.Rows.Add(row);
    }
}
 
private void MakeChildTable()
{
    // Create a new DataTable.
    DataTable table = new DataTable("childTable");
    DataColumn column;
    DataRow row;
 
    // Create first column and add to the DataTable.
    column = new DataColumn();
    column.DataType= System.Type.GetType("System.Int32");
    column.ColumnName = "ChildID";
    column.AutoIncrement = true;
    column.Caption = "ID";
    column.ReadOnly = true;
    column.Unique = true;

    // Add the column to the DataColumnCollection.
    table.Columns.Add(column);
 
    // Create second column.
    column = new DataColumn();
    column.DataType= System.Type.GetType("System.String");
    column.ColumnName = "ChildItem";
    column.AutoIncrement = false;
    column.Caption = "ChildItem";
    column.ReadOnly = false;
    column.Unique = false;
    table.Columns.Add(column);
 
    // Create third column.
    column = new DataColumn();
    column.DataType= System.Type.GetType("System.Int32");
    column.ColumnName = "ParentID";
    column.AutoIncrement = false;
    column.Caption = "ParentID";
    column.ReadOnly = false;
    column.Unique = false;
    table.Columns.Add(column);
 
    dataSet.Tables.Add(table);

    // Create three sets of DataRow objects, 
    // five rows each, and add to DataTable.
    for(int i = 0; i <= 4; i ++)
    {
        row = table.NewRow();
        row["childID"] = i;
        row["ChildItem"] = "Item " + i;
        row["ParentID"] = 0 ;
        table.Rows.Add(row);
    }
    for(int i = 0; i <= 4; i ++)
    {
        row = table.NewRow();
        row["childID"] = i + 5;
        row["ChildItem"] = "Item " + i;
        row["ParentID"] = 1 ;
        table.Rows.Add(row);
    }
    for(int i = 0; i <= 4; i ++)
    {
        row = table.NewRow();
        row["childID"] = i + 10;
        row["ChildItem"] = "Item " + i;
        row["ParentID"] = 2 ;
        table.Rows.Add(row);
    }
}
 
private void MakeDataRelation()
{
    // DataRelation requires two DataColumn 
    // (parent and child) and a name.
    DataColumn parentColumn = 
        dataSet.Tables["ParentTable"].Columns["id"];
    DataColumn childColumn = 
        dataSet.Tables["ChildTable"].Columns["ParentID"];
    DataRelation relation = new 
        DataRelation("parent2Child", parentColumn, childColumn);
    dataSet.Tables["ChildTable"].ParentRelations.Add(relation);
}
 
private void BindToDataGrid()
{
    // Instruct the DataGrid to bind to the DataSet, with the 
    // ParentTable as the topmost DataTable.
    dataGrid1.SetDataBinding(dataSet,"ParentTable");
}

继承层次结构

System.Object
System.ComponentModel.MarshalByValueComponent
System.Data.DataTable

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。

通过

DataTable 类

语法

备注

示例

继承层次结构

线程安全

平台

版本信息

.NET Framework

.NET Compact Framework

请参见

参考

其他资源

其他资源