执行多次更新并无差异——你只需重复使用SqlDataReader对象即可。在同一个数据库中从一个表往另一个表复制是对bcp的误用。另一方面，从外部文件中输入数据是一个常见的操作。
列表C在将一个文本文件输入到前一个例子中用到的表中时就采用了这个方法。（列表D中是对应的VB.NET代码。）这段代码建立一个新的DataTable对象，为每种数据设立列。
每次读入一行文件，并用逗号分列，每个数据值分配给DataTable中适当的列。接下来，SqlBulkCopy类的ColumnMappings属性允许你使用列名称，将数据源中（我们的DataTable）的一个列映射到目的地。完成映射后，WriteToServer方法使用提交给它的DataTable执行批量操作。 数据移植最佳实践
虽然数据移植是开发者经常要执行的任务，但它并不是一个非常流行的任务。请在文后的讨论部分与.NET社区分享你的最轻松（最糟糕）的数据移植经历和最佳实践。
――――――――――――――――――――――――――― using System;
using System.Collections.Generic; using System.Text;
using System.Data.SqlClient; namespace BCP { class Program { static void Main(){
string cString = \
ID=tester;Password=tester;Initial Catalog=Northwind;\ using (SqlConnectionconn = new SqlConnection(cString))
{
conn.Open(); SqlCommand comm = new SqlCommand(\EmployeeID, FirstName, LastName, HomePhone FROM Employees;\
SqlDataReader reader = comm.ExecuteReader();
using (SqlConnection conn2 = new SqlConnection(cString)){ conn2.Open();
using (SqlBulkCopy bcp = new SqlBulkCopy(conn2)) {
bcp.DestinationTableName = \ try {
bcp.WriteToServer(reader); } catch (Exception ex) {
Console.WriteLine(ex.Message); } finally { reader.Close(); } } } } } } }
―――――――――――――――――――――――――――
Imports System.Data.SqlClient Module Module1 Sub Main()
Dim cString As String
cString = \Catalog=Northwind;\
Dim conn As New SqlConnection conn = New SqlConnection(cString) conn.Open()
Dim comm As SqlCommand
comm Dim reader As SqlDataReader reader = comm.ExecuteReader() Dim conn2 As SqlConnection
conn2 = New SqlConnection(cString) conn2.Open()
Dim bcp As SqlBulkCopy
bcp = New SqlBulkCopy(conn2)
bcp.DestinationTableName = \ Try
bcp.WriteToServer(reader) Catch ex As Exception
Console.WriteLine(ex.Message) Finally
reader.Close() End Try End Sub End Module
using System;
using System.Collections.Generic; using System.Text;
using System.Data.SqlClient; using System.IO; using System.Data; namespace BCP { class Program{
static void Main(){
string cString = \
ID=tester;Password=tester;Initial Catalog=Northwind;\ using (SqlConnectionconn = new SqlConnection(cString)) { conn.Open();
SqlCommandcomm = new SqlCommand(\FirstName, LastName, HomePhone, Title FROM Employees;\
SqlDataReader reader = comm.ExecuteReader();
using (SqlConnection conn2 = new SqlConnection(cString)) { conn2.Open();
using (SqlBulkCopybcp = new SqlBulkCopy(conn2)){ DataTabledt = new DataTable(); DataRowdr;
DataColumn dc;
bcp.DestinationTableName = \ dc = new DataColumn(); dc.ColumnName = \dt.Columns.Add(dc); dc = new DataColumn(); dc.ColumnName = \dt.Columns.Add(dc); dc = new DataColumn();
dc.ColumnName = \dt.Columns.Add(dc); dc = new DataColumn(); dc.ColumnName = \dt.Columns.Add(dc);
StreamReadersr = new StreamReader(@\ string input;
while ((input = sr.ReadLine()) != null) { string[] s = input.Split(new char[] ); dr = dt.NewRow(); dr[\dr[\dr[\dr[\dt.Rows.Add(dr); }
sr.Close(); try {
bcp.ColumnMappings.Add(\bcp.ColumnMappings.Add(\bcp.ColumnMappings.Add(\
bcp.ColumnMappings.Add(\bcp.WriteToServer(dt);
} catch (Exception ex){
Console.WriteLine(ex.Message); } finally { reader.Close(); } } } } } } }
Imports System.Data
Imports System.Data.SqlClient Imports System.IO Module Module1 Sub Main()
Dim cString As String Dim comma As Char comma = \
cString = \Catalog=Northwind;\
Dim conn As New SqlConnection conn = New SqlConnection(cString) conn.Open()
Dim comm As SqlCommand comm = New SqlCommand(\EmployeeID, FirstName, LastName, HomePhone FROM Employees;\
Dim reader As SqlDataReader reader = comm.ExecuteReader() Dim conn2 As SqlConnection
conn2 = New SqlConnection(cString) conn2.Open()
Dim bcp As SqlBulkCopy
bcp = New SqlBulkCopy(conn2)
bcp.DestinationTableName = \ Try
Dim dt As DataTable Dim dr As DataRow Dim dc As DataColumn dt = New DataTable()
bcp.DestinationTableName = \ dc = New DataColumn() dc.ColumnName = \dt.Columns.Add(dc) dc = New DataColumn() dc.ColumnName = \dt.Columns.Add(dc) dc = New DataColumn()
dc.ColumnName = \
dt.Columns.Add(dc) dc = New DataColumn() dc.ColumnName = \dt.Columns.Add(dc)
Dim sr As StreamReader
sr = New StreamReader(\ Dim input As String input = sr.ReadLine()
While Not (input Is Nothing) Dim s As String()
s = input.Split(comma) dr = dt.NewRow() dr(\dr(\dr(\dr(\dt.Rows.Add(dr)
input = sr.ReadLine() End While sr.Close()
bcp.ColumnMappings.Add(\bcp.ColumnMappings.Add(\bcp.ColumnMappings.Add(\
bcp.ColumnMappings.Add(\bcp.WriteToServer(dt) Catch ex As Exception
Console.WriteLine(ex.Message) Finally
reader.Close() End Try End Sub End Module