SqlBulkCopyColumnMappingCollection.RemoveAt(Int32) Método
Definición
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.
Quita de la colección la asignación en el índice especificado.
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 -> unitoverride this.RemoveAt : int -> unitPublic Sub RemoveAt (index As Integer)Parámetros
- index
- Int32
Índice de base cero del objeto SqlBulkCopyColumnMapping que se va a quitar de la colección.
Implementaciones
Ejemplos
En el ejemplo siguiente se realizan dos operaciones de copia masiva. La primera operación copia la información del encabezado del pedido de ventas y la segunda copia los detalles del pedido de venta. Aunque no es estrictamente necesario en este ejemplo (porque las posiciones ordinales de las columnas de origen y de destino coinciden), el ejemplo define las asignaciones de columnas para cada operación de copia masiva. Ambas copias masivas incluyen una asignación para SalesOrderID, por lo que, en lugar de borrar toda la colección entre operaciones de copia masiva, el ejemplo quita todas las asignaciones excepto la asignación SalesOrderID y, a continuación, agrega las asignaciones adecuadas para la segunda operación de copia masiva.
Importante
Este ejemplo no se ejecuta a menos que haya creado las tablas de trabajo como se describe en Configuración de ejemplos de copia masiva. Este código se proporciona para mostrar la sintaxis para usar SqlBulkCopy. Si las tablas de origen y destino están en la misma instancia de SQL Server, es más fácil y rápido usar una instrucción Transact-SQL INSERT ... SELECT para copiar los datos.
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
Comentarios
El RemoveAt método se usa con más frecuencia cuando se usa una sola SqlBulkCopy instancia para procesar más de una operación de copia masiva. Si crea asignaciones de columnas para una operación de copia masiva, debe quitar las asignaciones que ya no se aplican después de llamar al WriteToServer método y antes de definir la asignación para la siguiente copia masiva. Puede borrar toda la colección mediante el Clear método o quitar asignaciones individualmente mediante el Remove método o el RemoveAt método .
La realización de varias copias masivas con la misma SqlBulkCopy instancia normalmente será más eficaz desde un punto de vista de rendimiento que el uso de una operación independiente SqlBulkCopy para cada operación.
Se aplica a
Consulte también
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