SQL Server FileStream 功能的詳細(xì)參考聯(lián)機(jī)幫助設(shè)計(jì)和實(shí)現(xiàn) FILESTREAM 存儲(chǔ)
這里只是把使用 Win32 管理 FILESTREAM 數(shù)據(jù)的代碼調(diào)整了一下，實(shí)現(xiàn)帶進(jìn)度的存取，這對(duì)于存取較大的文件比較有意義
要使用FileStream，首先要在 SQL Server配置管理器中打開(kāi)FileStream選項(xiàng)：SQL Server配置管理器–SQL Server服務(wù)–右邊的服務(wù)列表中找到SQL Server服務(wù)–屬性–FILESTREAM–允許遠(yuǎn)程客戶(hù)端訪(fǎng)問(wèn)FILESTREAM數(shù)據(jù)根據(jù)需要選擇，其他兩薦都選上。配置完成后，需要重新啟動(dòng)SQL Server服務(wù)使設(shè)置生效。
然后使用下面的腳本創(chuàng)建測(cè)試數(shù)據(jù)庫(kù)和測(cè)試表

 -- =========================================================-- 啟用 filestream_access_level-- =========================================================EXEC sp_configure 'filestream_access_level', 2;     -- 0=禁用  1=針對(duì) T-SQL 訪(fǎng)問(wèn)啟用 FILESTREAM  2=針對(duì) T-SQL 和 WIN32 流訪(fǎng)問(wèn)啟用 FILESTREAMRECONFIGURE;
GO-- =========================================================-- 創(chuàng)建測(cè)試數(shù)據(jù)庫(kù)-- =========================================================EXEC master..xp_create_subdir 'f:\temp\db\_test';CREATE DATABASE _testON
    PRIMARY(
        NAME = _test, FILENAME = 'f:\temp\db\_test\_test.mdf'),
    FILEGROUP FG_stream CONTAINS FILESTREAM(
        NAME = _test_file_stream, FILENAME = 'f:\temp\db\_test\stream')
    LOG ON(
        NAME = _test_log, FILENAME = 'f:\temp\db\_test\_test.ldf')
;GO-- =========================================================-- FileStream-- =========================================================-- =================================================-- 創(chuàng)建 包含 FileStream 數(shù)據(jù)的表-- -------------------------------------------------CREATE TABLE _test.dbo.tb_fs(
    id uniqueidentifier ROWGUIDCOL      -- 必需        DEFAULT NEWSEQUENTIALID ( ) PRIMARY KEY,
    name nvarchar(260),
    content varbinary(max) FILESTREAM
);GO

下面的 VB 腳本實(shí)現(xiàn)帶進(jìn)度顯示的文件存(Write方法）取（Read方法）

Imports System.IO
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlTypes
Module Module1
    Public Sub Main(ByVal args As String())
        Dim sqlConnection As New SqlConnection("Integrated Security=true;server=localhost")
        Try
            sqlConnection.Open()
            Console.WriteLine("將文件保存到 FileStream")
            Write(sqlConnection, "test", "f:\temp\re.csv")
            Console.WriteLine("從 FileStream 讀取數(shù)據(jù)保存到文件")
            Read(sqlConnection, "test", "f:\temp\re_1.csv")
        Catch ex As System.Exception
            Console.WriteLine(ex.ToString())
        Finally
            sqlConnection.Close()        End Try
        Console.WriteLine("處理結(jié)束，按 Enter 退出")
        Console.ReadLine()    End Sub    ''' <summary>
    ''' 將文件保存到數(shù)據(jù)庫(kù)    ''' </summary>
    ''' <param name="conn">數(shù)據(jù)庫(kù)連接</param>    ''' <param name="name">名稱(chēng)</param>
    ''' <param name="file">文件名</param>
    Sub Write(ByVal conn As SqlConnection, ByVal name As String, ByVal file As String)
        Dim bufferSize As Int32 = 1024
        Using sqlCmd As New SqlCommand
            sqlCmd.Connection = conn            '事務(wù)
            Dim transaction As SqlTransaction = conn.BeginTransaction("mainTranaction")
            sqlCmd.Transaction = transaction
            '1. 讀取 FILESTREAM 文件路徑 ( 注意函數(shù)大小寫(xiě) )
            sqlCmd.CommandText = "
UPDATE _test.dbo.tb_fs SET content = 0x WHERE name = @name;
IF @@ROWCOUNT = 0 INSERT _test.dbo.tb_fs(name, content) VALUES( @name, 0x );
SELECT content.PathName() FROM _test.dbo.tb_fs WHERE name = @name;"
            sqlCmd.Parameters.Add(New SqlParameter("name", name))
            Dim filePath As String = Nothing
            Dim pathObj As Object = sqlCmd.ExecuteScalar()            If Not pathObj.Equals(DBNull.Value) Then
                filePath = DirectCast(pathObj, String)            Else
                Throw New System.Exception("content.PathName() failed to read the path name for the content column.")            End If
            '2. 讀取當(dāng)前事務(wù)上下文
            sqlCmd.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"
            Dim obj As Object = sqlCmd.ExecuteScalar()
            Dim txContext As Byte() = Nothing
            Dim contextLength As UInteger
            If Not obj.Equals(DBNull.Value) Then
                txContext = DirectCast(obj, Byte())
                contextLength = txContext.Length()
            Else
                Dim message As String = "GET_FILESTREAM_TRANSACTION_CONTEXT() failed"
                Throw New System.Exception(message)
            End If
            '3. 獲取 Win32 句柄，并使用該句柄在 FILESTREAM BLOB 中讀取和寫(xiě)入數(shù)據(jù)            Using sqlFileStream As New SqlFileStream(filePath, txContext, FileAccess.Write)
                Dim buffer As Byte() = New Byte(bufferSize - 1) {}
                Dim numBytes As Integer = 0
                Using fsRead As New FileStream(file, FileMode.Open)
                    While True
                        numBytes = fsRead.Read(buffer, 0, bufferSize)                        If numBytes = 0 Then Exit While
                        sqlFileStream.Write(buffer, 0, numBytes)
                        Console.WriteLine(String.Format("{0} -> {1} -> {2}", fsRead.Position, sqlFileStream.Position, numBytes))                    End While
                    fsRead.Close()                End Using
                sqlFileStream.Close()            End Using
            sqlCmd.Transaction.Commit()        End Using
    End Sub    ''' <summary>
    ''' 從數(shù)據(jù)庫(kù)讀取數(shù)據(jù)保存到文件    ''' </summary>
    ''' <param name="conn">數(shù)據(jù)庫(kù)連接</param>    ''' <param name="name">名稱(chēng)</param>
    ''' <param name="file">文件名</param>
    Sub Read(ByVal conn As SqlConnection, ByVal name As String, ByVal file As String)
        Dim bufferSize As Int32 = 1024
        Using sqlCmd As New SqlCommand
            sqlCmd.Connection = conn            '1. 讀取 FILESTREAM 文件路徑 ( 注意函數(shù)大小寫(xiě) )
            sqlCmd.CommandText = "SELECT content.PathName() FROM _test.dbo.tb_fs WHERE name = @name;"
            sqlCmd.Parameters.Add(New SqlParameter("name", name))
            Dim filePath As String = Nothing
            Dim pathObj As Object = sqlCmd.ExecuteScalar()
            If Not pathObj.Equals(DBNull.Value) Then
                filePath = DirectCast(pathObj, String)
            Else
                Throw New System.Exception("content.PathName() failed to read the path name for the content column.")
            End If
            '2. 讀取當(dāng)前事務(wù)上下文
            Dim transaction As SqlTransaction = conn.BeginTransaction("mainTranaction")
            sqlCmd.Transaction = transaction
            sqlCmd.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"
            Dim obj As Object = sqlCmd.ExecuteScalar()
            Dim txContext As Byte() = Nothing
            Dim contextLength As UInteger            If Not obj.Equals(DBNull.Value) Then
                txContext = DirectCast(obj, Byte())
                contextLength = txContext.Length()            Else
                Dim message As String = "GET_FILESTREAM_TRANSACTION_CONTEXT() failed"
                Throw New System.Exception(message)            End If
            '3. 獲取 Win32 句柄，并使用該句柄在 FILESTREAM BLOB 中讀取和寫(xiě)入數(shù)據(jù)
            Using sqlFileStream As New SqlFileStream(filePath, txContext, FileAccess.Read)
                Dim buffer As Byte() = New Byte(bufferSize - 1) {}
                Dim numBytes As Integer = 0
                Using fsRead As New FileStream(file, FileMode.Create)
                    While True
                        numBytes = sqlFileStream.Read(buffer, 0, bufferSize)
                        If numBytes = 0 Then Exit While
                        fsRead.Write(buffer, 0, numBytes)
                        Console.WriteLine(String.Format("{0} -> {1} -> {2}", sqlFileStream.Position, sqlFileStream.Position, numBytes))
                    End While
                    fsRead.Close()
                End Using
                sqlFileStream.Close()
            End Using
            sqlCmd.Transaction.Commit()
        End Using
    End Sub
End Module

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