SqlBulkCopyColumnMappingCollection.Remove(SqlBulkCopyColumnMapping) Methode
Definition
Wichtig
Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.
Entfernt das angegebene SqlBulkCopyColumnMapping Element aus der SqlBulkCopyColumnMappingCollection.
public:
void Remove(System::Data::SqlClient::SqlBulkCopyColumnMapping ^ value);public void Remove(System.Data.SqlClient.SqlBulkCopyColumnMapping value);member this.Remove : System.Data.SqlClient.SqlBulkCopyColumnMapping -> unitPublic Sub Remove (value As SqlBulkCopyColumnMapping)Parameter
- value
- SqlBulkCopyColumnMapping
SqlBulkCopyColumnMapping objekt, das aus der Auflistung entfernt werden soll.
Beispiele
Im folgenden Beispiel werden zwei Massenkopievorgänge ausgeführt. Der erste Vorgang kopiert Die Kopfzeileninformationen des Verkaufsauftrags und die zweite Kopiert Die Details der Verkaufsauftragsbestellung. Obwohl in diesem Beispiel nicht unbedingt erforderlich (da die Ordnungspositionen der Quell- und Zielspalten übereinstimmen), definiert das Beispiel Spaltenzuordnungen für jeden Massenkopievorgang. Beide Massenkopien enthalten eine Zuordnung für die SalesOrderID. Anstatt die gesamte Auflistung zwischen Massenkopievorgängen zu löschen, entfernt das Beispiel alle Zuordnungen mit Ausnahme der SalesOrderID-Zuordnung und fügt dann die entsprechenden Zuordnungen für den zweiten Massenkopievorgang hinzu.
Important
Dieses Beispiel wird nur ausgeführt, wenn Sie die Arbeitstabellen zuvor wie unter Beispiel für die Einrichtung des Massenkopierens beschrieben erstellt haben. Der angegebene Code dient nur zur Demonstration der Syntax für die Verwendung von SqlBulkCopy. Wenn sich die Quell- und Zieltabellen in derselben SQL Server-Instanz befinden, ist es einfacher und schneller, eine Transact-SQL-Anweisung INSERT ... SELECT zum Kopieren der Daten zu verwenden.
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");
// Define SqlBulkCopyColumnMapping objects so they
// can be referenced later.
SqlBulkCopyColumnMapping columnMappingDate =
bulkCopy.ColumnMappings.Add("OrderDate", "OrderDate");
SqlBulkCopyColumnMapping columnMappingAccount =
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 Remove method.
bulkCopy.ColumnMappings.Remove(columnMappingDate);
bulkCopy.ColumnMappings.Remove(columnMappingAccount);
// 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")
' Define SqlBulkCopyColumnMapping objects so they
' can be referenced later.
Dim columnMappingDate As SqlBulkCopyColumnMapping = _
bulkCopy.ColumnMappings.Add("OrderDate", "OrderDate")
Dim columnMappingAccount As SqlBulkCopyColumnMapping = _
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 Remove method.
bulkCopy.ColumnMappings.Remove(columnMappingDate)
bulkCopy.ColumnMappings.Remove(columnMappingAccount)
' 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
Hinweise
Die Remove Methode wird am häufigsten verwendet, wenn Sie eine einzelne SqlBulkCopy Instanz verwenden, um mehrere Massenkopievorgänge zu verarbeiten. Wenn Sie Spaltenzuordnungen für einen Massenkopievorgang erstellen, müssen Sie Zuordnungen entfernen, die nicht mehr angewendet werden, nachdem die WriteToServer Methode aufgerufen wurde, und bevor Sie die Zuordnung für die nächste Massenkopie definieren. Sie können die gesamte Sammlung mithilfe der Clear Methode löschen oder Zuordnungen einzeln mithilfe der Remove Methode oder der RemoveAt Methode entfernen.
Das Ausführen mehrerer Massenkopien mit derselben Instanz ist in der SqlBulkCopy Regel effizienter als die Verwendung eines separaten SqlBulkCopy Vorgangs.
