SqlBulkCopyColumnMappingCollection.RemoveAt(Int32) Yöntem

public:
 virtual void RemoveAt(int index);

public:
 void RemoveAt(int index);

public void RemoveAt (int index);

abstract member RemoveAt : int -> unit
override this.RemoveAt : int -> unit

override this.RemoveAt : int -> unit

Public Sub RemoveAt (index As Integer)

Parametreler

Uygulamalar

Örnekler

Aşağıdaki örnek iki toplu kopyalama işlemi gerçekleştirir. İlk işlem satış siparişi üst bilgisi bilgilerini, ikinci işlem ise satış siparişi ayrıntılarını kopyalar. Bu örnekte kesinlikle gerekli olmasa da (kaynak ve hedef sütunların sıralı konumları eşleştiği için), örnek her toplu kopyalama işlemi için sütun eşlemelerini tanımlar. Her iki toplu kopya da SalesOrderID için bir eşleme içerir. Bu nedenle örnek, toplu kopyalama işlemleri arasında koleksiyonun tamamını temizlemek yerine SalesOrderID eşlemesi dışındaki tüm eşlemeleri kaldırır ve ardından ikinci toplu kopyalama işlemi için uygun eşlemeleri ekler.

using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = GetConnectionString();
        // Open a connection to the AdventureWorks database.
        using (SqlConnection connection =
                   new SqlConnection(connectionString))
        {
            connection.Open();

            // Empty the destination tables.
            SqlCommand deleteHeader = new SqlCommand(
                "DELETE FROM dbo.BulkCopyDemoOrderHeader;",
                connection);
            deleteHeader.ExecuteNonQuery();
            SqlCommand deleteDetail = new SqlCommand(
                "DELETE FROM dbo.BulkCopyDemoOrderDetail;",
                connection);
            deleteDetail.ExecuteNonQuery();

            // Perform an initial count on the destination
            //  table with matching columns.
            SqlCommand countRowHeader = new SqlCommand(
                "SELECT COUNT(*) FROM dbo.BulkCopyDemoOrderHeader;",
                connection);
            long countStartHeader = System.Convert.ToInt32(
                countRowHeader.ExecuteScalar());
            Console.WriteLine(
                "Starting row count for Header table = {0}",
                countStartHeader);

            // Perform an initial count on the destination
            // table with different column positions.
            SqlCommand countRowDetail = new SqlCommand(
                "SELECT COUNT(*) FROM dbo.BulkCopyDemoOrderDetail;",
                connection);
            long countStartDetail = System.Convert.ToInt32(
                countRowDetail.ExecuteScalar());
            Console.WriteLine(
                "Starting row count for Detail table = {0}",
                countStartDetail);

            // Get data from the source table as a SqlDataReader.
            // The Sales.SalesOrderHeader and Sales.SalesOrderDetail
            // tables are quite large and could easily cause a timeout
            // if all data from the tables is added to the destination.
            // To keep the example simple and quick, a parameter is
            // used to select only orders for a particular account
            // as the source for the bulk insert.
            SqlCommand headerData = new SqlCommand(
                "SELECT [SalesOrderID], [OrderDate], " +
                "[AccountNumber] FROM [Sales].[SalesOrderHeader] " +
                "WHERE [AccountNumber] = @accountNumber;",
                connection);
            SqlParameter parameterAccount = new SqlParameter();
            parameterAccount.ParameterName = "@accountNumber";
            parameterAccount.SqlDbType = SqlDbType.NVarChar;
            parameterAccount.Direction = ParameterDirection.Input;
            parameterAccount.Value = "10-4020-000034";
            headerData.Parameters.Add(parameterAccount);
            SqlDataReader readerHeader = headerData.ExecuteReader();

            // Get the Detail data in a separate connection.
            using (SqlConnection connection2 = new SqlConnection(connectionString))
            {
                connection2.Open();
                SqlCommand sourceDetailData = new SqlCommand(
                    "SELECT [Sales].[SalesOrderDetail].[SalesOrderID], [SalesOrderDetailID], " +
                    "[OrderQty], [ProductID], [UnitPrice] FROM [Sales].[SalesOrderDetail] " +
                    "INNER JOIN [Sales].[SalesOrderHeader] ON [Sales].[SalesOrderDetail]." +
                    "[SalesOrderID] = [Sales].[SalesOrderHeader].[SalesOrderID] " +
                    "WHERE [AccountNumber] = @accountNumber;", connection2);

                    SqlParameter accountDetail = new SqlParameter();
                    accountDetail.ParameterName = "@accountNumber";
                    accountDetail.SqlDbType = SqlDbType.NVarChar;
                    accountDetail.Direction = ParameterDirection.Input;
                    accountDetail.Value = "10-4020-000034";
                    sourceDetailData.Parameters.Add(accountDetail);
                    SqlDataReader readerDetail = sourceDetailData.ExecuteReader();

                // Create the SqlBulkCopy object.
                using (SqlBulkCopy bulkCopy =
                           new SqlBulkCopy(connectionString))
                {
                    bulkCopy.DestinationTableName =
                        "dbo.BulkCopyDemoOrderHeader";

                    // Guarantee that columns are mapped correctly by
                    // defining the column mappings for the order.
                    bulkCopy.ColumnMappings.Add("SalesOrderID", "SalesOrderID");
                    bulkCopy.ColumnMappings.Add("OrderDate", "OrderDate");
                    bulkCopy.ColumnMappings.Add("AccountNumber", "AccountNumber");

                    // Write readerHeader to the destination.
                    try
                    {
                        bulkCopy.WriteToServer(readerHeader);
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    finally
                    {
                        readerHeader.Close();
                    }

                    // Set up the order details destination.
                    bulkCopy.DestinationTableName ="dbo.BulkCopyDemoOrderDetail";

                    // Rather than clearing mappings that are not necessary
                    // for the next bulk copyo peration, the unneeded mappings
                    //  are removed with the RemoveAt method.
                    bulkCopy.ColumnMappings.RemoveAt(2);
                    bulkCopy.ColumnMappings.RemoveAt(1);

                    // Add order detail column mappings.
                    bulkCopy.ColumnMappings.Add("SalesOrderDetailID", "SalesOrderDetailID");
                    bulkCopy.ColumnMappings.Add("OrderQty", "OrderQty");
                    bulkCopy.ColumnMappings.Add("ProductID", "ProductID");
                    bulkCopy.ColumnMappings.Add("UnitPrice", "UnitPrice");
                    bulkCopy.WriteToServer(readerDetail);

                    // Write readerDetail to the destination.
                    try
                    {
                        bulkCopy.WriteToServer(readerDetail);
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    finally
                    {
                        readerDetail.Close();
                    }
                }

                // Perform a final count on the destination
                // tables to see how many rows were added.
                long countEndHeader = System.Convert.ToInt32(
                    countRowHeader.ExecuteScalar());
                Console.WriteLine("{0} rows were added to the Header table.",
                    countEndHeader - countStartHeader);
                long countEndDetail = System.Convert.ToInt32(
                    countRowDetail.ExecuteScalar());
                Console.WriteLine("{0} rows were added to the Detail table.",
                    countEndDetail - countStartDetail);
                Console.WriteLine("Press Enter to finish.");
                Console.ReadLine();
            }
        }
    }

    private static string GetConnectionString()
        // To avoid storing the connection string in your code,
        // you can retrieve it from a configuration file.
    {
        return "Data Source=(local); " +
            " Integrated Security=true;" +
            "Initial Catalog=AdventureWorks;";
    }
}

Imports System.Data.SqlClient

Module Module1
    Sub Main()
        Dim connectionString As String = GetConnectionString()

        ' Open a connection to the AdventureWorks database.
        Using connection As SqlConnection = New SqlConnection(connectionString)
            connection.Open()

            ' Empty the destination tables.
            Dim deleteHeader As New SqlCommand( _
              "DELETE FROM dbo.BulkCopyDemoOrderHeader;", connection)
            deleteHeader.ExecuteNonQuery()
            deleteHeader.Dispose()
            Dim deleteDetail As New SqlCommand( _
              "DELETE FROM dbo.BulkCopyDemoOrderDetail;", connection)
            deleteDetail.ExecuteNonQuery()

            ' Perform an initial count on the destination table 
            ' with matching columns.
            Dim countRowHeader As New SqlCommand( _
               "SELECT COUNT(*) FROM dbo.BulkCopyDemoOrderHeader;", _
                connection)
            Dim countStartHeader As Long = System.Convert.ToInt32( _
             countRowHeader.ExecuteScalar())
            Console.WriteLine("Starting row count for Header table = {0}", _
             countStartHeader)

            ' Perform an initial count on the destination table 
            ' with different column positions.
            Dim countRowDetail As New SqlCommand( _
                "SELECT COUNT(*) FROM dbo.BulkCopyDemoOrderDetail;", _
                connection)
            Dim countStartDetail As Long = System.Convert.ToInt32( _
                countRowDetail.ExecuteScalar())
            Console.WriteLine("Starting row count for Detail table = " & _
               countStartDetail)

            ' Get data from the source table as a SqlDataReader.
            ' The Sales.SalesOrderHeader and Sales.SalesOrderDetail
            ' tables are quite large and could easily cause a timeout
            ' if all data from the tables is added to the destination.
            ' To keep the example simple and quick, a parameter is 
            ' used to select only orders for a particular account as
            ' the source for the bulk insert.
            Dim headerData As SqlCommand = New SqlCommand( _
             "SELECT [SalesOrderID], [OrderDate], " & _
             "[AccountNumber] FROM [Sales].[SalesOrderHeader] " & _
             "WHERE [AccountNumber] = @accountNumber;", _
             connection)

            Dim parameterAccount As SqlParameter = New SqlParameter()
            parameterAccount.ParameterName = "@accountNumber"
            parameterAccount.SqlDbType = SqlDbType.NVarChar
            parameterAccount.Direction = ParameterDirection.Input
            parameterAccount.Value = "10-4020-000034"
            headerData.Parameters.Add(parameterAccount)

            Dim readerHeader As SqlDataReader = _
             headerData.ExecuteReader()

            ' Get the Detail data in a separate connection.
            Using connection2 As SqlConnection = New SqlConnection(connectionString)
                connection2.Open()

                Dim sourceDetailData As SqlCommand = New SqlCommand( _
                 "SELECT [Sales].[SalesOrderDetail].[SalesOrderID], " & _
                 "[SalesOrderDetailID], [OrderQty], [ProductID], [UnitPrice] " & _
                 "FROM [Sales].[SalesOrderDetail] INNER JOIN " & _
                 "[Sales].[SalesOrderHeader] " & _
                 "ON [Sales].[SalesOrderDetail].[SalesOrderID] = " & _
                 "[Sales].[SalesOrderHeader].[SalesOrderID] " & _
                 "WHERE [AccountNumber] = @accountNumber;", connection2)

                Dim accountDetail As SqlParameter = New SqlParameter()
                accountDetail.ParameterName = "@accountNumber"
                accountDetail.SqlDbType = SqlDbType.NVarChar
                accountDetail.Direction = ParameterDirection.Input
                accountDetail.Value = "10-4020-000034"
                sourceDetailData.Parameters.Add( _
                 accountDetail)

                Dim readerDetail As SqlDataReader = _
                 sourceDetailData.ExecuteReader()

                ' Create the SqlBulkCopy object.
                Using bulkCopy As SqlBulkCopy = _
                  New SqlBulkCopy(connectionString)
                    bulkCopy.DestinationTableName = "dbo.BulkCopyDemoOrderHeader"

                    ' Guarantee that columns are mapped correctly by
                    ' defining the column mappings for the order.
                    bulkCopy.ColumnMappings.Add("SalesOrderID", "SalesOrderID")
                    bulkCopy.ColumnMappings.Add("OrderDate", "OrderDate")
                    bulkCopy.ColumnMappings.Add("AccountNumber", "AccountNumber")
 
                   ' Write readerHeader to the destination.
                    Try
                        bulkCopy.WriteToServer(readerHeader)
                    Catch ex As Exception
                        Console.WriteLine(ex.Message)
                    Finally
                        readerHeader.Close()
                    End Try

                    ' Set up the order details destination.
                    bulkCopy.DestinationTableName = "dbo.BulkCopyDemoOrderDetail"

                    ' Rather than clearing mappings that are not necessary
                    ' for the next bulk copy operation, the unneeded         
                    ' mappings are removed with the RemoveAt method.
                    bulkCopy.ColumnMappings.RemoveAt(2)
                    bulkCopy.ColumnMappings.RemoveAt(1)

                    ' Add order detail column mappings.
                    bulkCopy.ColumnMappings.Add("SalesOrderDetailID", "SalesOrderDetailID")
                    bulkCopy.ColumnMappings.Add("OrderQty", "OrderQty")
                    bulkCopy.ColumnMappings.Add("ProductID", "ProductID")
                    bulkCopy.ColumnMappings.Add("UnitPrice", "UnitPrice")

                    ' Write readerDetail to the destination.
                    Try
                        bulkCopy.WriteToServer(readerDetail)
                    Catch ex As Exception
                        Console.WriteLine(ex.Message)
                    Finally
                        readerDetail.Close()
                    End Try
                End Using

                ' Perform a final count on the destination tables
                ' to see how many rows were added.
                Dim countEndHeader As Long = System.Convert.ToInt32( _
                  countRowHeader.ExecuteScalar())
                Console.WriteLine("{0} rows were added to the Header table.", _
                  countEndHeader - countStartHeader)
                Dim countEndDetail As Long = System.Convert.ToInt32( _
                   countRowDetail.ExecuteScalar())
                Console.WriteLine("{0} rows were added to the Detail table.", _
                    countEndDetail - countStartDetail)

                Console.WriteLine("Press Enter to finish.")
                Console.ReadLine()
            End Using
        End Using
    End Sub

    Private Function GetConnectionString() As String
        ' To avoid storing the connection string in your code, 
        ' you can retrieve it from a configuration file. 
        Return "Data Source=(local);" & _
            "Integrated Security=true;" & _
            "Initial Catalog=AdventureWorks;"
    End Function
End Module

Açıklamalar

RemoveAt yöntemi en yaygın olarak, birden fazla toplu kopyalama işlemini işlemek için tek SqlBulkCopy bir örnek kullandığınızda kullanılır. Tek bir toplu kopyalama işlemi için sütun eşlemeleri oluşturursanız, yöntem çağrıldıktan sonra WriteToServer ve sonraki toplu kopyalama için eşleme tanımlamadan önce artık geçerli olmayan eşlemeleri kaldırmanız gerekir. yöntemini kullanarak Clear koleksiyonun tamamını temizleyebilir veya yöntemini veya yöntemini RemoveAt kullanarak Remove eşlemeleri tek tek kaldırabilirsiniz.

Aynı SqlBulkCopy örneği kullanarak birkaç toplu kopya gerçekleştirmek genellikle performans açısından her işlem için ayrı SqlBulkCopy bir kopya kullanmaktan daha verimli olacaktır.

Şunlara uygulanır

Ayrıca bkz.

• SQL Server’da Toplu Kopyalama İşlemleri
• ADO.NET’e Genel Bakış