DataSet.CreateDataReader Método

Referencia

Definición

Espacio de nombres:: System.Data

Ensamblado:: System.Data.Common.dll

Ensamblado:: System.Data.dll

Ensamblado:: netstandard.dll

Importante

Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.

Devuelve un objeto DataTableReader con un conjunto de resultados por cada DataTable, siguiendo la misma secuencia con la que aparecen las tablas en la colección Tables.

Sobrecargas

CreateDataReader(DataTable[])	Devuelve un objeto DataTableReader con un conjunto de resultados por cada DataTable.
CreateDataReader()	Devuelve un objeto DataTableReader con un conjunto de resultados por cada DataTable, siguiendo la misma secuencia con la que aparecen las tablas en la colección Tables.

Ejemplos

En este ejemplo, una aplicación de consola, crea tres DataTable instancias y agrega cada una a .DataSet En el ejemplo se llama al CreateDataReader método y se muestra el contenido del devuelto DataTableReader. Tenga en cuenta que el orden de los conjuntos de resultados en DataTableReader se controla mediante el orden de las DataTable instancias pasadas como parámetros.

Nota

En este ejemplo se muestra cómo usar una de las versiones sobrecargadas de CreateDataReader. Para ver otros ejemplos que podrían estar disponibles, consulte los temas de sobrecarga individuales.

static DataTable customerTable;
static DataTable productTable;
static DataTable emptyTable;

static void Main()
{
    DataSet dataSet = new DataSet();

    // Add some DataTables to the DataSet, including
    // an empty DataTable:
    emptyTable = new DataTable();
    productTable = GetProducts();
    customerTable = GetCustomers();

    dataSet.Tables.Add(customerTable);
    dataSet.Tables.Add(emptyTable);
    dataSet.Tables.Add(productTable);
    TestCreateDataReader(dataSet);

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

private static void TestCreateDataReader(DataSet dataSet)
{
    // Given a DataSet, retrieve a DataTableReader
    // allowing access to all the DataSet's data.
    // Even though the dataset contains three DataTables,
    // this code will only display the contents of two of them,
    // because the code has limited the results to the
    // DataTables stored in the tables array. Because this
    // parameter is declared using the ParamArray keyword,
    // you could also include a list of DataTable instances
    // individually, as opposed to supplying an array of
    // DataTables, as in this example:
    using (DataTableReader reader =
        dataSet.CreateDataReader(productTable, emptyTable))
    {
        do
        {
            if (!reader.HasRows)
            {
                Console.WriteLine("Empty DataTableReader");
            }
            else
            {
                PrintColumns(reader);
            }
            Console.WriteLine("========================");
        } while (reader.NextResult());
    }
}

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" });
    table.AcceptChanges();
    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" });
    table.AcceptChanges();
    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 emptyTable As DataTable
Private customerTable As DataTable
Private productTable As DataTable

Sub Main()
  Dim dataSet As New DataSet
  ' Add some DataTables to the DataSet, including
  ' an empty DataTable:

  emptyTable = New DataTable()
  productTable = GetProducts()
  customerTable = GetCustomers()

  dataSet.Tables.Add(customerTable)
  dataSet.Tables.Add(emptyTable)
  dataSet.Tables.Add(productTable)
  TestCreateDataReader(dataSet)

  Console.WriteLine("Press any key to continue.")
  Console.ReadKey()
End Sub

Private Sub TestCreateDataReader(ByVal dataSet As DataSet)
  ' Given a DataSet, retrieve a DataTableReader
  ' allowing access to all the DataSet's data.
  ' Even though the dataset contains three DataTables,
  ' this code will only display the contents of two of them,
  ' because the code has limited the results to the 
  ' DataTables stored in the tables array. Because this
  ' parameter is declared using the ParamArray keyword, 
  ' you could also include a list of DataTable instances 
  ' individually, as opposed to supplying an array of 
  ' DataTables, as in this example:
  Using reader As DataTableReader = _
      dataSet.CreateDataReader(productTable, emptyTable)
    Do
      If Not reader.HasRows Then
        Console.WriteLine("Empty DataTableReader")
      Else
        PrintColumns(reader)
      End If
      Console.WriteLine("========================")
    Loop While reader.NextResult()
  End Using
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"})
  table.AcceptChanges()
  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"})
  table.AcceptChanges()
  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

En el ejemplo se muestra el código siguiente en la ventana Consola:

Comentarios

Para garantizar el orden de los conjuntos de resultados en el devuelto DataTableReader, si un DataTable elemento dentro DataSet de está vacío, se representará mediante un conjunto de resultados vacío dentro del devuelto DataTableReader.

CreateDataReader(DataTable[])

Devuelve un objeto DataTableReader con un conjunto de resultados por cada DataTable.

public:
 System::Data::DataTableReader ^ CreateDataReader(... cli::array <System::Data::DataTable ^> ^ dataTables);

public System.Data.DataTableReader CreateDataReader (params System.Data.DataTable[] dataTables);

member this.CreateDataReader : System.Data.DataTable[] -> System.Data.DataTableReader

Public Function CreateDataReader (ParamArray dataTables As DataTable()) As DataTableReader

Parámetros

dataTables: DataTable[]

Matriz de objetos DataTable que proporciona el orden de los conjuntos de resultados que va a devolver el objeto DataTableReader.

Devoluciones

DataTableReader

Objeto DataTableReader que contiene uno o varios conjuntos de resultados, que se corresponden con las instancias de DataTable incluidas en el objeto DataSet de origen. Los conjuntos de resultados devueltos siguen el orden especificado por el parámetro dataTables.

Ejemplos

static DataTable customerTable;
static DataTable productTable;
static DataTable emptyTable;

static void Main()
{
    DataSet dataSet = new DataSet();

    // Add some DataTables to the DataSet, including
    // an empty DataTable:
    emptyTable = new DataTable();
    productTable = GetProducts();
    customerTable = GetCustomers();

    dataSet.Tables.Add(customerTable);
    dataSet.Tables.Add(emptyTable);
    dataSet.Tables.Add(productTable);
    TestCreateDataReader(dataSet);

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

private static void TestCreateDataReader(DataSet dataSet)
{
    // Given a DataSet, retrieve a DataTableReader
    // allowing access to all the DataSet's data.
    // Even though the dataset contains three DataTables,
    // this code will only display the contents of two of them,
    // because the code has limited the results to the
    // DataTables stored in the tables array. Because this
    // parameter is declared using the ParamArray keyword,
    // you could also include a list of DataTable instances
    // individually, as opposed to supplying an array of
    // DataTables, as in this example:
    using (DataTableReader reader =
       dataSet.CreateDataReader(productTable, emptyTable))
    {
        do
        {
            if (!reader.HasRows)
            {
                Console.WriteLine("Empty DataTableReader");
            }
            else
            {
                PrintColumns(reader);
            }
            Console.WriteLine("========================");
        } while (reader.NextResult());
    }
}

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 emptyTable As DataTable
Private customerTable As DataTable
Private productTable As DataTable

Sub Main()
  Dim dataSet As New DataSet
  ' Add some DataTables to the DataSet, including
  ' an empty DataTable:

  emptyTable = New DataTable()
  productTable = GetProducts()
  customerTable = GetCustomers()

  dataSet.Tables.Add(customerTable)
  dataSet.Tables.Add(emptyTable)
  dataSet.Tables.Add(productTable)
  TestCreateDataReader(dataSet)

  Console.WriteLine("Press any key to continue.")
  Console.ReadKey()
End Sub

Private Sub TestCreateDataReader(ByVal dataSet As DataSet)
  ' Given a DataSet, retrieve a DataTableReader
  ' allowing access to all the DataSet's data.
  ' Even though the dataset contains three DataTables,
  ' this code will only display the contents of two of them,
  ' because the code has limited the results to the 
  ' DataTables stored in the tables array. Because this
  ' parameter is declared using the ParamArray keyword, 
  ' you could also include a list of DataTable instances 
  ' individually, as opposed to supplying an array of 
  ' DataTables, as in this example:
  Using reader As DataTableReader = _
    dataSet.CreateDataReader(productTable, emptyTable)
    Do
      If Not reader.HasRows Then
        Console.WriteLine("Empty DataTableReader")
      Else
        PrintColumns(reader)
      End If
      Console.WriteLine("========================")
    Loop While reader.NextResult()
  End Using
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

Comentarios

Para asegurarse de que el orden de los conjuntos de resultados dentro del objeto devuelto DataTableReaderes , si un DataTable elemento dentro DataSet de está vacío, se representa mediante un conjunto de resultados vacío dentro del devuelto DataTableReader. Dado que esta versión sobrecargada permite proporcionar una lista de DataTable instancias como parámetros, puede especificar el orden en el que aparecen los conjuntos de resultados en el devuelto DataTableReader.

Consulte también

Uso de conjuntos de datos en ADO.NET

Se aplica a

CreateDataReader()

Devuelve un objeto DataTableReader con un conjunto de resultados por cada DataTable, siguiendo la misma secuencia con la que aparecen las tablas en la colección Tables.

public:
 System::Data::DataTableReader ^ CreateDataReader();

public System.Data.DataTableReader CreateDataReader ();

member this.CreateDataReader : unit -> System.Data.DataTableReader

Public Function CreateDataReader () As DataTableReader

Devoluciones

DataTableReader

Objeto DataTableReader que contiene uno o varios conjuntos de resultados, que se corresponden con las instancias de DataTable incluidas en el objeto DataSet de origen.

Ejemplos

En el ejemplo siguiente se crean tres DataTable instancias y se agrega cada una a .DataSet A continuación, el ejemplo pasa el relleno DataSet a un procedimiento que llama al CreateDataReader método y continúa para recorrer en iteración todos los conjuntos de resultados contenidos en .DataTableReader En el ejemplo se muestran los resultados en la ventana Consola.

static void Main()
{
    DataSet dataSet = new DataSet();
    // Add some DataTables to the DataSet, including
    // an empty DataTable:
    dataSet.Tables.Add(GetCustomers());
    dataSet.Tables.Add(new DataTable());
    dataSet.Tables.Add(GetProducts());
    TestCreateDataReader(dataSet);

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

private static void TestCreateDataReader(DataSet dataSet)
{
    // Given a DataSet, retrieve a DataTableReader
    // allowing access to all the DataSet's data:
    using (DataTableReader reader = dataSet.CreateDataReader())
    {
        do
        {
            if (!reader.HasRows)
            {
                Console.WriteLine("Empty DataTableReader");
            }
            else
            {
                PrintColumns(reader);
            }
            Console.WriteLine("========================");
        } while (reader.NextResult());
    }
}

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();
    }
}

Sub Main()
  Dim dataSet As New DataSet
  ' Add some DataTables to the DataSet, including
  ' an empty DataTable:
  dataSet.Tables.Add(GetCustomers())
  dataSet.Tables.Add(New DataTable())
  dataSet.Tables.Add(GetProducts())
  TestCreateDataReader(dataSet)

  Console.WriteLine("Press any key to continue.")
  Console.ReadKey()
End Sub

Private Sub TestCreateDataReader(ByVal dataSet As DataSet)
  ' Given a DataSet, retrieve a DataTableReader
  ' allowing access to all the DataSet's data:
  Using reader As DataTableReader = dataSet.CreateDataReader()
    Do
      If Not reader.HasRows Then
        Console.WriteLine("Empty DataTableReader")
      Else
        PrintColumns(reader)
      End If
      Console.WriteLine("========================")
    Loop While reader.NextResult()
  End Using
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

Comentarios

Para garantizar el orden de los conjuntos de resultados en el devuelto DataTableReader, si un DataTable objeto dentro DataSet de está vacío, se representa mediante un conjunto de resultados vacío dentro del devuelto DataTableReader.

Consulte también

Uso de conjuntos de datos en ADO.NET

Se aplica a

DataSet.CreateDataReader Método

Definición

Sobrecargas

Ejemplos

Comentarios

CreateDataReader(DataTable[])

Parámetros

Devoluciones

Ejemplos

Comentarios

Consulte también

Se aplica a

CreateDataReader()

Devoluciones

Ejemplos

Comentarios

Consulte también

Se aplica a

Recursos adicionales