帶進度的SQL Server FileStream怎么存取
發表時間:2023-07-13 來源:明輝站整理相關軟件相關文章人氣:
[摘要]SQL Server FileStream 功能的詳細參考聯機幫助設計和實現 FILESTREAM 存儲 這里只是把使用 Win32 管理 FILESTREAM 數據的代碼調整了一下,實現帶進度的存...
SQL Server FileStream 功能的詳細參考聯機幫助設計和實現 FILESTREAM 存儲
這里只是把使用 Win32 管理 FILESTREAM 數據的代碼調整了一下,實現帶進度的存取,這對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FileStream選項:SQL Server配置管理器–SQL Server服務–右邊的服務列表中找到SQL Server服務–屬性–FILESTREAM–允許遠程客戶端訪問FILESTREAM數據根據需要選擇,其他兩薦都選上。配置完成后,需要重新啟動SQL Server服務使設置生效。
然后使用下面的腳本創建測試數據庫和測試表
-- =========================================================-- 啟用 filestream_access_level-- =========================================================EXEC sp_configure 'filestream_access_level', 2; -- 0=禁用 1=針對 T-SQL 訪問啟用 FILESTREAM 2=針對 T-SQL 和 WIN32 流訪問啟用 FILESTREAMRECONFIGURE;
GO-- =========================================================-- 創建測試數據庫-- =========================================================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-- =========================================================-- =================================================-- 創建 包含 FileStream 數據的表-- -------------------------------------------------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 腳本實現帶進度顯示的文件存(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 讀取數據保存到文件")
Read(sqlConnection, "test", "f:\temp\re_1.csv")
Catch ex As System.Exception
Console.WriteLine(ex.ToString())
Finally
sqlConnection.Close() End Try
Console.WriteLine("處理結束,按 Enter 退出")
Console.ReadLine() End Sub ''' <summary>
''' 將文件保存到數據庫 ''' </summary>
''' <param name="conn">數據庫連接</param> ''' <param name="name">名稱</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
Dim transaction As SqlTransaction = conn.BeginTransaction("mainTranaction")
sqlCmd.Transaction = transaction
'1. 讀取 FILESTREAM 文件路徑 ( 注意函數大小寫 )
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. 讀取當前事務上下文
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 中讀取和寫入數據 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>
''' 從數據庫讀取數據保存到文件 ''' </summary>
''' <param name="conn">數據庫連接</param> ''' <param name="name">名稱</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 ( 注意函數大小寫 )
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. 讀取當前事務上下文
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 中讀取和寫入數據
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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