DataSet.CreateDataReader DataSet.CreateDataReader DataSet.CreateDataReader DataSet.CreateDataReader Method

定义

为每个 DataTableReader 返回带有一个结果集的 DataTable,顺序与 Tables 集合中表的显示顺序相同。Returns a DataTableReader with one result set per DataTable, in the same sequence as the tables appear in the Tables collection.

重载

CreateDataReader(DataTable[]) CreateDataReader(DataTable[]) CreateDataReader(DataTable[]) CreateDataReader(DataTable[])

为每个 DataTableReader 返回带有一个结果集的 DataTableReturns a DataTableReader with one result set per DataTable.

CreateDataReader() CreateDataReader() CreateDataReader() CreateDataReader()

为每个 DataTableReader 返回带有一个结果集的 DataTable,顺序与 Tables 集合中表的显示顺序相同。Returns a DataTableReader with one result set per DataTable, in the same sequence as the tables appear in the Tables collection.

示例

此示例是一个控制台应用程序,它DataTable创建三个实例,并DataSet将每个实例添加到中。This example, a Console application, creates three DataTable instances and adds each to a DataSet. 该示例调用CreateDataReader方法,并显示返回DataTableReader的的内容。The example calls the CreateDataReader method and displays the contents of the returned DataTableReader. 请注意,中DataTableReader的结果集的顺序由作为参数传递的DataTable实例的顺序控制。Note that the order of the result sets in the DataTableReader is controlled by the order of the DataTable instances passed as parameters.

备注

此示例演示如何使用的重载版本CreateDataReader之一。This example shows how to use one of the overloaded versions of CreateDataReader. 有关可能可用的其他示例,请参阅各个重载主题。For other examples that might be available, see the individual overload topics.

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

该示例在控制台窗口中显示以下代码:The example displays the following code in the Console window:

注解

为了确保返回DataTableReader的中的结果集的顺序, DataTable如果中DataSet的为空,则将在返回DataTableReader的内由空的结果集表示。In order to ensure the order of the result sets within the returned DataTableReader, if a DataTable within the DataSet is empty, it will be represented by an empty result set within the returned DataTableReader.

CreateDataReader(DataTable[]) CreateDataReader(DataTable[]) CreateDataReader(DataTable[]) CreateDataReader(DataTable[])

为每个 DataTableReader 返回带有一个结果集的 DataTableReturns a DataTableReader with one result set per 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

参数

dataTables
DataTable[]

一个 DataTable 数组,它提供要在 DataTableReader 中返回的结果集的顺序。An array of DataTables providing the order of the result sets to be returned in the DataTableReader.

返回

包含一个或多个结果集的 DataTableReader,与源 DataTable 中包含的 DataSet 实例相对应。A DataTableReader containing one or more result sets, corresponding to the DataTable instances contained within the source DataSet. 返回的结果集按 dataTables 参数所指定的顺序排列。The returned result sets are in the order specified by the dataTables parameter.

示例

此示例是一个控制台应用程序,它DataTable创建三个实例,并DataSet将每个实例添加到中。This example, a Console application, creates three DataTable instances and adds each to a DataSet. 该示例调用CreateDataReader方法,并显示返回DataTableReader的的内容。The example calls the CreateDataReader method and displays the contents of the returned DataTableReader. 请注意,中DataTableReader的结果集的顺序由作为参数传递的DataTable实例的顺序控制。Note that the order of the result sets in the DataTableReader is controlled by the order of the DataTable instances passed as parameters. 该示例在控制台窗口中显示结果。The example displays the results in the Console window.

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

注解

为了确保返回DataTableReader的中的结果集的顺序为空, DataTable如果中DataSet的为空,则它由返回DataTableReader的中的空结果集表示。In order to ensure that the order of the result sets within the returned DataTableReader, if a DataTable within the DataSet is empty, it is represented by an empty result set within the returned DataTableReader. 由于此重载版本允许您将DataTable实例列表作为参数提供,因此您可以指定结果集在返回DataTableReader的中的显示顺序。Because this overloaded version allows you to supply a list of DataTable instances as parameters, you can specify the order in which the result sets appear within the returned DataTableReader.

另请参阅

CreateDataReader() CreateDataReader() CreateDataReader() CreateDataReader()

为每个 DataTableReader 返回带有一个结果集的 DataTable,顺序与 Tables 集合中表的显示顺序相同。Returns a DataTableReader with one result set per DataTable, in the same sequence as the tables appear in the Tables collection.

public:
 System::Data::DataTableReader ^ CreateDataReader();
public System.Data.DataTableReader CreateDataReader ();
member this.CreateDataReader : unit -> System.Data.DataTableReader
Public Function CreateDataReader () As DataTableReader

返回

包含一个或多个结果集的 DataTableReader,与源 DataTable 中包含的 DataSet 实例相对应。A DataTableReader containing one or more result sets, corresponding to the DataTable instances contained within the source DataSet.

示例

下面的示例创建三DataTable个实例,并将每个DataSet实例添加到中。The following example creates three DataTable instances, and adds each to a DataSet. 然后,该示例将填充DataSet的传递给CreateDataReader调用方法的过程,并继续循环访问中包含的所有DataTableReader结果集。The example then passes the filled DataSet to a procedure that calls the CreateDataReader method, and proceeds to iterate through all the result sets contained within the DataTableReader. 该示例在控制台窗口中显示结果。The example displays the results in the Console window.

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

注解

为了确保返回DataTableReader的中的结果集的顺序, DataTable如果中DataSet的为空,则它由返回DataTableReader的中的空结果集表示。In order to ensure the order of the result sets within the returned DataTableReader, if a DataTable within the DataSet is empty, it is represented by an empty result set within the returned DataTableReader.

另请参阅

适用于