DataTableReader Konstruktoren

Definition

Initialisiert eine neue Instanz der DataTableReader-Klasse.Initializes a new instance of the DataTableReader class.

Überlädt

DataTableReader(DataTable)

Initialisiert unter Verwendung von Daten aus der bereitgestellten DataTableReader eine neue Instanz der DataTable-Klasse.Initializes a new instance of the DataTableReader class by using data from the supplied DataTable.

DataTableReader(DataTable[])

Initialisiert eine neue Instanz der DataTableReader-Klasse unter Verwendung des bereitgestellten Arrays von DataTable-Objekten.Initializes a new instance of the DataTableReader class using the supplied array of DataTable objects.

DataTableReader(DataTable)

Initialisiert unter Verwendung von Daten aus der bereitgestellten DataTableReader eine neue Instanz der DataTable-Klasse.Initializes a new instance of the DataTableReader class by using data from the supplied DataTable.

public:
 DataTableReader(System::Data::DataTable ^ dataTable);
public DataTableReader (System.Data.DataTable dataTable);
new System.Data.DataTableReader : System.Data.DataTable -> System.Data.DataTableReader
Public Sub New (dataTable As DataTable)

Parameter

dataTable
DataTable

Die DataTable, von der der neue DataTableReader sein Resultset erhält.The DataTable from which the new DataTableReader obtains its result set.

DataTableReader(DataTable[])

Initialisiert eine neue Instanz der DataTableReader-Klasse unter Verwendung des bereitgestellten Arrays von DataTable-Objekten.Initializes a new instance of the DataTableReader class using the supplied array of DataTable objects.

public:
 DataTableReader(cli::array <System::Data::DataTable ^> ^ dataTables);
public DataTableReader (System.Data.DataTable[] dataTables);
new System.Data.DataTableReader : System.Data.DataTable[] -> System.Data.DataTableReader
Public Sub New (dataTables As DataTable())

Parameter

dataTables
DataTable[]

Das Array von DataTable-Objekten, das die Ergebnisse für das neue DataTableReader-Objekt bereitstellt.The array of DataTable objects that supplies the results for the new DataTableReader object.

Beispiele

Im folgenden Beispiel erstellt die TestConstructor-Methode zwei DataTable-Instanzen.In the following example, the TestConstructor method creates two DataTable instances. Um diesen Konstruktor für die DataTableReader-Klasse zu veranschaulichen, erstellt das Beispiel einen neuen DataTableReader basierend auf einem Array, das die beiden DataTablesenthält, und führt einen einfachen Vorgang aus, der den Inhalt aus den ersten Spalten in das Konsolenfenster druckt.In order to demonstrate this constructor for the DataTableReader class, the sample creates a new DataTableReader based on an array that contains the two DataTables, and performs a simple operation, printing the contents from the first few columns to the console window. Um diese Anwendung zu testen, erstellen Sie eine neue Konsolenanwendung, und fügen Sie den Beispielcode in die neu erstellte Datei ein.In order to test this application, create a new Console application, and paste the sample code into the newly created file.

private static void TestConstructor()
{
    // Create two data adapters, one for each of the two
    // DataTables to be filled.
    DataTable customerDataTable = GetCustomers();
    DataTable productDataTable = GetProducts();

    // Create the new DataTableReader.
    using (DataTableReader reader = new DataTableReader(
               new DataTable[] { customerDataTable, productDataTable }))
    {
        // Print the contents of each of the result sets.
        do
        {
            PrintColumns(reader);
        } while (reader.NextResult());
    }

    Console.WriteLine("Press Enter to finish.");
    Console.ReadLine();
}

private static DataTable GetCustomers()
{
    // Create sample Customers table, in order
    // to demonstrate the behavior of the DataTableReader.
    DataTable table = new DataTable();
  
    // Create two columns, ID and Name.
    DataColumn idColumn = table.Columns.Add("ID", typeof(int));
    table.Columns.Add("Name", typeof(string ));
  
    // Set the ID column as the primary key column.
    table.PrimaryKey = new DataColumn[] { idColumn };

    table.Rows.Add(new object[] { 1, "Mary" });
    table.Rows.Add(new object[] { 2, "Andy" });
    table.Rows.Add(new object[] { 3, "Peter" });
    table.Rows.Add(new object[] { 4, "Russ" });
    return table;
}

private static DataTable GetProducts()
{
    // Create sample Products table, in order
    // to demonstrate the behavior of the DataTableReader.
    DataTable table = new DataTable();
  
    // Create two columns, ID and Name.
    DataColumn idColumn = table.Columns.Add("ID", typeof(int));
    table.Columns.Add("Name", typeof(string ));
  
    // Set the ID column as the primary key column.
    table.PrimaryKey = new DataColumn[] { idColumn };

    table.Rows.Add(new object[] { 1, "Wireless Network Card" });
    table.Rows.Add(new object[] { 2, "Hard Drive" });
    table.Rows.Add(new object[] { 3, "Monitor" });
    table.Rows.Add(new object[] { 4, "CPU" });
    return table;
}

private static void PrintColumns(DataTableReader reader)
{
    // Loop through all the rows in the DataTableReader
    while (reader.Read())
    {
        for (int i = 0; i < reader.FieldCount; i++)
        {
            Console.Write(reader[i] + " ");
        }
        Console.WriteLine();
    }
}
Private Sub TestConstructor()
   ' Create two data adapters, one for each of the two
   ' DataTables to be filled.
   Dim customerDataTable As DataTable = GetCustomers()
   Dim productDataTable As DataTable = GetProducts()

   ' Create the new DataTableReader.
   Using reader As New DataTableReader( _
      New DataTable() {customerDataTable, productDataTable})

      ' Print the contents of each of the result sets.
      Do
         PrintColumns(reader)
      Loop While reader.NextResult()
   End Using

   Console.WriteLine("Press Enter to finish.")
   Console.ReadLine()

End Sub

Private Function GetCustomers() As DataTable
   ' Create sample Customers table, in order
   ' to demonstrate the behavior of the DataTableReader.
   Dim table As New DataTable

   ' Create two columns, ID and Name.
   Dim idColumn As DataColumn = table.Columns.Add("ID", _
     GetType(Integer))
   table.Columns.Add("Name", GetType(String))

   ' Set the ID column as the primary key column.
   table.PrimaryKey = New DataColumn() {idColumn}

   table.Rows.Add(New Object() {1, "Mary"})
   table.Rows.Add(New Object() {2, "Andy"})
   table.Rows.Add(New Object() {3, "Peter"})
   table.Rows.Add(New Object() {4, "Russ"})
   Return table
End Function

Private Function GetProducts() As DataTable
   ' Create sample Products table, in order
   ' to demonstrate the behavior of the DataTableReader.
   Dim table As New DataTable

   ' Create two columns, ID and Name.
   Dim idColumn As DataColumn = table.Columns.Add("ID", _
     GetType(Integer))
   table.Columns.Add("Name", GetType(String))

   ' Set the ID column as the primary key column.
   table.PrimaryKey = New DataColumn() {idColumn}

   table.Rows.Add(New Object() {1, "Wireless Network Card"})
   table.Rows.Add(New Object() {2, "Hard Drive"})
   table.Rows.Add(New Object() {3, "Monitor"})
   table.Rows.Add(New Object() {4, "CPU"})
   Return table
End Function

Private Sub PrintColumns( _
   ByVal reader As DataTableReader)

   ' Loop through all the rows in the DataTableReader.
   Do While reader.Read()
      For i As Integer = 0 To reader.FieldCount - 1
         Console.Write(reader(i).ToString() & " ")
      Next
      Console.WriteLine()
   Loop
End Sub

Im Konsolenfenster werden folgende Ergebnisse angezeigt:The Console window displays the following results:

1 Mary  
2 Andy  
3 Peter  
4 Russ  
1 Wireless Network Card  
2 Hard Drive  
3 Monitor  
4 CPU  

Hinweise

Wenn Sie eine DataTableReader basierend auf allen oder einer Teilmenge der Tabellen in einer bestimmten DataSeterstellen müssen, rufen Sie die CreateDataReader-Methode des DataSetauf.If you must create a DataTableReader based on all or a subset of the tables within a specific DataSet, call the DataSet's CreateDataReader method. Wenn Sie eine neue DataTableReader-Instanz erstellen möchten, die auf einer Gruppe von DataTable Instanzen basiert, die ansonsten nicht verknüpft sind, verwenden Sie diesen Konstruktor.If you want to create a new DataTableReader instance based on a group of DataTable instances that are not otherwise related, use this constructor. Sie können diesen Konstruktor auch verwenden, um die Reihenfolge der DataTables innerhalb des DataTableReaderneu anzuordnen, wenn die Reihenfolge innerhalb des Quell DataSet Ihren Anforderungen nicht entspricht.You can also take advantage of this constructor to rearrange the ordering of the DataTables within the DataTableReader, if their ordering within their source DataSet does not meet your needs.

Gilt für: