SqlBulkCopyColumnMappingCollection.RemoveAt(Int32) Metodo
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Rimuove il mapping dall'insieme in corrispondenza dell'indice specificato.
public:
void RemoveAt(int index);public:
virtual void RemoveAt(int index);public void RemoveAt (int index);override this.RemoveAt : int -> unitabstract member RemoveAt : int -> unit
override this.RemoveAt : int -> unitPublic Sub RemoveAt (index As Integer)Parametri
- index
- Int32
Indice in base zero dell'oggetto SqlBulkCopyColumnMapping da rimuovere dall'insieme.
Implementazioni
Esempio
Nell'esempio seguente vengono eseguite due operazioni di copia bulk. La prima operazione copia le informazioni sull'intestazione dell'ordine di vendita e la seconda copia i dettagli dell'ordine di vendita. Anche se non è strettamente necessario in questo esempio (perché le posizioni ordinali delle colonne di origine e di destinazione corrispondono), l'esempio definisce i mapping di colonne per ogni operazione di copia bulk. Entrambe le copie bulk includono un mapping per SalesOrderID, quindi anziché cancellare l'intera raccolta tra operazioni di copia bulk, l'esempio rimuove tutti i mapping tranne il mapping SalesOrderID e quindi aggiunge i mapping appropriati per la seconda operazione di copia bulk.
Importante
Questo esempio non verrà eseguito a meno che non siano state create le tabelle di lavoro, come descritto in Installazione di esempio di copia bulk. Il codice viene fornito solo per illustrare la sintassi relativa all'uso di SqlBulkCopy. Se le tabelle di origine e di destinazione si trovano nella stessa istanza di SQL Server, è più semplice e veloce usare un'istruzione Transact-SQL INSERT ... SELECT per copiare i dati.
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
Commenti
Il RemoveAt metodo viene usato più comunemente quando si usa una singola SqlBulkCopy istanza per elaborare più operazioni di copia bulk. Se si creano mapping di colonne per un'operazione di copia bulk, è necessario rimuovere i mapping che non vengono più applicati dopo che il metodo viene chiamato e prima di definire il WriteToServer mapping per la copia bulk successiva. È possibile cancellare l'intera raccolta usando il metodo o rimuovere i mapping singolarmente usando il Clear metodo o il RemoveRemoveAt metodo .
L'esecuzione di diverse copie bulk usando la stessa SqlBulkCopy istanza sarà in genere più efficiente da un punto di vista delle prestazioni rispetto all'uso di un'operazione separata SqlBulkCopy per ogni operazione.
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