SqlBulkCopyColumnMappingCollection.Remove(SqlBulkCopyColumnMapping) 方法

定義

命名空間:

Microsoft.Data.SqlClient

組件:

Microsoft.Data.SqlClient.dll

套件:

Microsoft.Data.SqlClient v5.2.0

將指定的 SqlBulkCopyColumnMapping 項目從 SqlBulkCopyColumnMappingCollection 移除。

public:
 void Remove(Microsoft::Data::SqlClient::SqlBulkCopyColumnMapping ^ value);

public void Remove (Microsoft.Data.SqlClient.SqlBulkCopyColumnMapping value);

member this.Remove : Microsoft.Data.SqlClient.SqlBulkCopyColumnMapping -> unit

Public Sub Remove (value As SqlBulkCopyColumnMapping)

參數

value

SqlBulkCopyColumnMapping

要從集合移除的 SqlBulkCopyColumnMapping 物件。

範例

下列範例會執行兩個大量複製作業。 第一個作業會複製銷售訂單標頭資訊，而第二個作業會複製銷售訂單詳細資料。 雖然本範例中並非絕對必要 (，因為來源和目的地資料行的序數位置與) 相符，但此範例會定義每個大量複製作業的資料行對應。 這兩個大量複本都包含 SalesOrderID的對應，因此除了 SalesOrderID 對應之外，此範例會移除 SalesOrderID 對應以外的所有對應，然後新增第二個大量複製作業的適當對應。

重要

除非您已建立工作資料表，如 大量複製範例安裝程式中所述，否則不會執行此範例。 這個程式碼僅是為了示範使用 SqlBulkCopy 的語法而提供。 如果來源和目的地資料表位於相同的SQL Server實例中，使用 Transact-SQL INSERT … SELECT 語句來複製資料會比較簡單且更快速。

using System;
using System.Data;
using Microsoft.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";

                    // Clear the ColumnMappingCollection.
                    bulkCopy.ColumnMappings.Clear();

                    // Add order detail column mappings.
                    bulkCopy.ColumnMappings.Add("SalesOrderID", "SalesOrderID");
                    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 (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;";
    }
}

備註

當您 Remove 使用單 SqlBulkCopy 一實例來處理多個大量複製作業時，最常使用 方法。 如果您為一個大量複製作業建立資料行對應，則必須移除呼叫 方法之後 WriteToServer 不再套用的對應，以及在定義下一個大量複製的對應之前。 您可以使用 方法清除整個集合 Clear ，或使用 方法或 RemoveAt 方法個別 Remove 移除對應。

使用相同 SqlBulkCopy 實例執行數個大量複本通常比針對每個作業使用不同的 SqlBulkCopy 效能觀點更有效率。