DataTable Classe

Definição

public ref class DataTable : System::ComponentModel::MarshalByValueComponent, System::ComponentModel::IListSource, System::ComponentModel::ISupportInitialize, System::ComponentModel::ISupportInitializeNotification, System::Runtime::Serialization::ISerializable, System::Xml::Serialization::IXmlSerializable

public ref class DataTable

public ref class DataTable : System::ComponentModel::MarshalByValueComponent, System::ComponentModel::IListSource, System::ComponentModel::ISupportInitialize, System::Runtime::Serialization::ISerializable

public ref class DataTable : System::ComponentModel::MarshalByValueComponent, System::ComponentModel::IListSource, System::ComponentModel::ISupportInitializeNotification, System::Runtime::Serialization::ISerializable, System::Xml::Serialization::IXmlSerializable

[System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.NonPublicConstructors | System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)]
public class DataTable : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitialize, System.ComponentModel.ISupportInitializeNotification, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

public class DataTable : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitialize, System.ComponentModel.ISupportInitializeNotification, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

public class DataTable

[System.Serializable]
public class DataTable : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitialize, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class DataTable : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitializeNotification, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

public class DataTable : System.ComponentModel.MarshalByValueComponent, System.ComponentModel.IListSource, System.ComponentModel.ISupportInitializeNotification, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

[<System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.NonPublicConstructors | System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)>]
type DataTable = class
    inherit MarshalByValueComponent
    interface IListSource
    interface ISupportInitialize
    interface ISupportInitializeNotification
    interface ISerializable
    interface IXmlSerializable

type DataTable = class
    inherit MarshalByValueComponent
    interface IListSource
    interface ISupportInitialize
    interface ISupportInitializeNotification
    interface ISerializable
    interface IXmlSerializable

type DataTable = class

[<System.Serializable>]
type DataTable = class
    inherit MarshalByValueComponent
    interface IListSource
    interface ISupportInitialize
    interface ISerializable

[<System.Serializable>]
type DataTable = class
    inherit MarshalByValueComponent
    interface IListSource
    interface ISupportInitializeNotification
    interface ISupportInitialize
    interface ISerializable
    interface IXmlSerializable

Public Class DataTable
Inherits MarshalByValueComponent
Implements IListSource, ISerializable, ISupportInitialize, ISupportInitializeNotification, IXmlSerializable

Public Class DataTable

Public Class DataTable
Inherits MarshalByValueComponent
Implements IListSource, ISerializable, ISupportInitialize

Public Class DataTable
Inherits MarshalByValueComponent
Implements IListSource, ISerializable, ISupportInitializeNotification, IXmlSerializable

Herança

Object

MarshalByValueComponent

DataTable

Herança

Object

DataTable

Derivado

System.Data.TypedTableBase<T>

Atributos

DynamicallyAccessedMembersAttribute SerializableAttribute

Implementações

IListSource ISupportInitialize ISupportInitializeNotification ISerializable IXmlSerializable

Exemplos

Este exemplo demonstra como criar uma DataTable manualmente com definições de esquema específicas:

• Crie várias DataTables e defina as colunas iniciais.
• Crie as restrições de tabela.
• Insira os valores e exiba as tabelas.
• Crie as colunas de expressão e exiba as tabelas.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        // Create two tables and add them into the DataSet.
        DataTable orderTable = CreateOrderTable();
        DataTable orderDetailTable = CreateOrderDetailTable();
        DataSet salesSet = new();
        salesSet.Tables.Add(orderTable);
        salesSet.Tables.Add(orderDetailTable);

        // Set the relations between the tables
        // and create the related constraint.
        salesSet.Relations.Add(
            "OrderOrderDetail",
            orderTable.Columns["OrderId"],
            orderDetailTable.Columns["OrderId"],
            true);

        Console.WriteLine("After creating the foreign key constraint, " +
            "you'll see the following error if you insert " +
            "an order detail with the wrong OrderId:\n");
        try
        {
            DataRow errorRow = orderDetailTable.NewRow();
            errorRow[0] = 1;
            errorRow[1] = "O0007";
            orderDetailTable.Rows.Add(errorRow);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
        Console.WriteLine();

        // Insert the rows into the table.
        InsertOrders(orderTable);
        InsertOrderDetails(orderDetailTable);

        Console.WriteLine("The initial Order table.");
        ShowTable(orderTable);

        Console.WriteLine("The OrderDetail table.");
        ShowTable(orderDetailTable);

        // Use the Aggregate-Sum on the child table column to get the result.
        DataColumn colSub = new("SubTotal", typeof(decimal), "Sum(Child.LineTotal)");
        orderTable.Columns.Add(colSub);

        // Compute the tax by referencing the SubTotal expression column.
        DataColumn colTax = new("Tax", typeof(decimal), "SubTotal*0.1");
        orderTable.Columns.Add(colTax);

        // If the OrderId is 'Total', compute the amount due on all orders; otherwise, compute the amount due on this order.
        DataColumn colTotal = new(
            "TotalDue",
            typeof(decimal),
            "IIF(OrderId='Total',Sum(SubTotal)+Sum(Tax),SubTotal+Tax)");
        orderTable.Columns.Add(colTotal);

        DataRow row = orderTable.NewRow();
        row["OrderId"] = "Total";
        orderTable.Rows.Add(row);

        Console.WriteLine("The Order table with the expression columns.");
        ShowTable(orderTable);

        Console.WriteLine("Press any key to exit.....");
        Console.ReadKey();
    }

    private static DataTable CreateOrderTable()
    {
        DataTable orderTable = new("Order");

        // Define the columns one at a time.
        DataColumn colId = new("OrderId", typeof(string));
        orderTable.Columns.Add(colId);

        DataColumn colDate = new("OrderDate", typeof(DateTime));
        orderTable.Columns.Add(colDate);

        // Set the OrderId column as the primary key.
        orderTable.PrimaryKey = [colId];

        return orderTable;
    }

    private static DataTable CreateOrderDetailTable()
    {
        DataTable orderDetailTable = new("OrderDetail");

        // Define all the columns at once.
        DataColumn[] cols =
        [
            new DataColumn("OrderDetailId", typeof(int)),
            new DataColumn("OrderId", typeof(string)),
            new DataColumn("Product", typeof(string)),
            new DataColumn("UnitPrice", typeof(decimal)),
            new DataColumn("OrderQty", typeof(int)),
            new DataColumn("LineTotal", typeof(decimal), "UnitPrice*OrderQty")
        ];

        orderDetailTable.Columns.AddRange(cols);
        orderDetailTable.PrimaryKey = [orderDetailTable.Columns["OrderDetailId"]];
        return orderDetailTable;
    }

    private static void InsertOrders(DataTable orderTable)
    {
        // Add one row at a time.
        DataRow row1 = orderTable.NewRow();
        row1["OrderId"] = "O0001";
        row1["OrderDate"] = new DateTime(2013, 3, 1);
        orderTable.Rows.Add(row1);

        DataRow row2 = orderTable.NewRow();
        row2["OrderId"] = "O0002";
        row2["OrderDate"] = new DateTime(2013, 3, 12);
        orderTable.Rows.Add(row2);

        DataRow row3 = orderTable.NewRow();
        row3["OrderId"] = "O0003";
        row3["OrderDate"] = new DateTime(2013, 3, 20);
        orderTable.Rows.Add(row3);
    }

    private static void InsertOrderDetails(DataTable orderDetailTable)
    {
        // Use an Object array to insert all the rows.
        // Values in the array are matched sequentially to the columns,
        // based on the order in which they appear in the table.
        object[][] rows =
        [
            [1, "O0001", "Mountain Bike", 1419.5, 36],
            [2, "O0001", "Road Bike", 1233.6, 16],
            [3, "O0001", "Touring Bike", 1653.3, 32],
            [4, "O0002", "Mountain Bike", 1419.5, 24],
            [5, "O0002", "Road Bike", 1233.6, 12],
            [6, "O0003", "Mountain Bike", 1419.5, 48],
            [7, "O0003", "Touring Bike", 1653.3, 8],
        ];

        foreach (object[] row in rows)
        {
            orderDetailTable.Rows.Add(row);
        }
    }

    private static void ShowTable(DataTable table)
    {
        foreach (DataColumn col in table.Columns)
        {
            Console.Write("{0,-14}", col.ColumnName);
        }
        Console.WriteLine();

        foreach (DataRow row in table.Rows)
        {
            foreach (DataColumn col in table.Columns)
            {
                if (col.DataType.Equals(typeof(DateTime)))
                    Console.Write("{0,-14:d}", row[col]);
                else if (col.DataType.Equals(typeof(decimal)))
                    Console.Write("{0,-14:C}", row[col]);
                else
                    Console.Write("{0,-14}", row[col]);
            }
            Console.WriteLine();
        }
        Console.WriteLine();
    }
}

' 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 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 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

Observações

A DataTable classe é um objeto central na biblioteca ADO.NET. Outros objetos que usam DataTable incluem o DataSet e o DataView.

DataTable Os nomes dos objetos são sensíveis a maiúsculas e minúsculas condicionalmente. Por exemplo, se uma DataTable é chamada "mydatatable" e outra é chamada "Mydatatable", uma cadeia de caracteres usada para procurar uma das tabelas é considerada sensível a maiúsculas e minúsculas. No entanto, se "mydatatable" existir e "Mydatatable" não, a cadeia de caracteres de pesquisa será considerada insensível a maiúsculas e minúsculas. A DataSet pode conter dois DataTable objetos que têm o mesmo valor de propriedade TableName, mas diferentes valores de propriedade Namespace. Para obter mais informações sobre como trabalhar com DataTable objetos, consulte Criando uma DataTable.

Se estiveres a criar um DataTable programaticamente, deves primeiro definir o seu esquema adicionando objetos DataColumn ao DataColumnCollection através da propriedade Columns. Para obter mais informações sobre como adicionar DataColumn objetos, consulte Adicionando colunas a uma DataTable.

Para adicionar linhas a um DataTable, você deve primeiro usar o NewRow método para retornar um novo DataRow objeto. O método NewRow retorna uma linha com o esquema de DataTable, conforme definido pela tabela de DataColumnCollection. O número máximo de linhas que um DataTable pode armazenar é 16.777.216. Para obter mais informações, consulte Adicionando dados a uma DataTable.

O DataTable também contém uma coleção de Constraint objetos que podem ser usados para garantir a integridade dos dados. Para obter mais informações, consulte DataTable Constraints.

Há muitos DataTable eventos que podem ser usados para determinar quando as alterações são feitas em uma tabela. Estes incluem RowChanged, RowChanging, RowDeleting, e RowDeleted. Para obter mais informações sobre os eventos que podem ser usados com um DataTable, consulte Manipulando eventos DataTable.

Quando uma instância de DataTable é criada, algumas das suas propriedades de leitura/gravação são definidas como valores iniciais. Para obter uma lista desses valores, consulte o DataTable construtor.

Considerações de segurança

Para obter informações sobre a segurança DataSet e DataTable, consulte Diretrizes de segurança.

Segurança de Thread

Este tipo é seguro para operações de leitura multithread. Tem de sincronizar quaisquer operações de escrita.

Ver também

• Tabelas de dados