SqlBulkCopyColumnMappingCollection Classe

Definição

public ref class SqlBulkCopyColumnMappingCollection sealed : System::Collections::CollectionBase

public sealed class SqlBulkCopyColumnMappingCollection : System.Collections.CollectionBase

type SqlBulkCopyColumnMappingCollection = class
    inherit CollectionBase

Public NotInheritable Class SqlBulkCopyColumnMappingCollection
Inherits CollectionBase

Herança

Object

CollectionBase

SqlBulkCopyColumnMappingCollection

Exemplos

O exemplo a seguir copia dados em massa de uma tabela de origem no banco de dados de exemplo AdventureWorks para uma tabela de destino no mesmo banco de dados. Embora o número de colunas no destino corresponda ao número de colunas na origem, os nomes das colunas e as posições ordinais não correspondem. SqlBulkCopyColumnMapping são adicionados ao SqlBulkCopyColumnMappingCollection objeto para SqlBulkCopy criar um mapa de coluna para a cópia em massa.

using System.Data.SqlClient;

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

            // Perform an initial count on the destination table.
            SqlCommand commandRowCount = new SqlCommand(
                "SELECT COUNT(*) FROM " +
                "dbo.BulkCopyDemoDifferentColumns;",
                sourceConnection);
            long countStart = System.Convert.ToInt32(
                commandRowCount.ExecuteScalar());
            Console.WriteLine("Starting row count = {0}", countStart);

            // Get data from the source table as a SqlDataReader.
            SqlCommand commandSourceData = new SqlCommand(
                "SELECT ProductID, Name, " +
                "ProductNumber " +
                "FROM Production.Product;", sourceConnection);
            SqlDataReader reader =
                commandSourceData.ExecuteReader();

            // Set up the bulk copy object.
            using (SqlBulkCopy bulkCopy =
                       new SqlBulkCopy(connectionString))
            {
                bulkCopy.DestinationTableName =
                    "dbo.BulkCopyDemoDifferentColumns";

                // The column order in the source doesn't match the order
                // in the destination, so ColumnMappings must be defined.
                bulkCopy.ColumnMappings.Add("ProductID", "ProdID");
                bulkCopy.ColumnMappings.Add("Name", "ProdName");
                bulkCopy.ColumnMappings.Add("ProductNumber", "ProdNum");

                // Write from the source to the destination.
                try
                {
                    bulkCopy.WriteToServer(reader);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
                finally
                {
                    // Close the SqlDataReader. The SqlBulkCopy
                    // object is automatically closed at the end
                    // of the using block.
                    reader.Close();
                }
            }

            // Perform a final count on the destination
            // table to see how many rows were added.
            long countEnd = System.Convert.ToInt32(
                commandRowCount.ExecuteScalar());
            Console.WriteLine("Ending row count = {0}", countEnd);
            Console.WriteLine("{0} rows were added.", countEnd - countStart);
            Console.WriteLine("Press Enter to finish.");
            Console.ReadLine();
        }
    }

    private static string GetConnectionString()
        // To avoid storing the sourceConnection 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 sourceConnection As SqlConnection = _
           New SqlConnection(connectionString)
            sourceConnection.Open()

            ' Perform an initial count on the destination table.
            Dim commandRowCount As New SqlCommand( _
            "SELECT COUNT(*) FROM dbo.BulkCopyDemoDifferentColumns;", _
                sourceConnection)
            Dim countStart As Long = _
               System.Convert.ToInt32(commandRowCount.ExecuteScalar())
            Console.WriteLine("Starting row count = {0}", countStart)

            ' Get data from the source table as a SqlDataReader.
            Dim commandSourceData As SqlCommand = New SqlCommand( _
               "SELECT ProductID, Name, ProductNumber " & _
               "FROM Production.Product;", sourceConnection)
            Dim reader As SqlDataReader = commandSourceData.ExecuteReader

            ' Set up the bulk copy object.
            Using bulkCopy As SqlBulkCopy = New SqlBulkCopy(connectionString)
                bulkCopy.DestinationTableName = _
                "dbo.BulkCopyDemoDifferentColumns"

                ' The column order in the source doesn't match the order 
                ' in the destination, so ColumnMappings must be defined.
                bulkCopy.ColumnMappings.Add("ProductID", "ProdID")
                bulkCopy.ColumnMappings.Add("Name", "ProdName")
                bulkCopy.ColumnMappings.Add("ProductNumber", "ProdNum")

                ' Write from the source to the destination.
                Try
                    bulkCopy.WriteToServer(reader)

                Catch ex As Exception
                    Console.WriteLine(ex.Message)

                Finally
                    ' Close the SqlDataReader. The SqlBulkCopy
                    ' object is automatically closed at the end
                    ' of the Using block.
                    reader.Close()
                End Try
            End Using

            ' Perform a final count on the destination table
            ' to see how many rows were added.
            Dim countEnd As Long = _
                System.Convert.ToInt32(commandRowCount.ExecuteScalar())
            Console.WriteLine("Ending row count = {0}", countEnd)
            Console.WriteLine("{0} rows were added.", countEnd - countStart)

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

    Private Function GetConnectionString() As String
        ' To avoid storing the sourceConnection 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

Comentários

Os mapeamentos de coluna definem o mapeamento entre a fonte de dados e a tabela de destino.

Se os mapeamentos não estiverem definidos, ou seja, a ColumnMappings coleção estiver vazia, as colunas serão mapeadas implicitamente com base na posição ordinal. Para que isso funcione, os esquemas de origem e destino devem corresponder. Se não o fizerem, um InvalidOperationException é jogado.

Se a ColumnMappings coleção não estiver vazia, nem todas as colunas presentes na fonte de dados precisarão ser especificadas. Aqueles não mapeados pela coleção são ignorados.

Você pode se referir às colunas de origem e de destino por nome ou ordinal. Você pode misturar referências de coluna por nome e por ordinal na mesma coleção de mapeamentos.

Confira também

• Operações de cópia em massa no SQL Server
• Visão geral do ADO.NET