Detailed reference to the SQL Server FileStream function online help design and implementation of FILESTREAM storage
Here is just an adjustment of the code that uses Win32 to manage FILESTREAM data to achieve progressed access, which is more suitable for accessing larger files. Significant
To use FileStream, first turn on the FileStream option in SQL Server Configuration Manager: SQL Server Configuration Manager – SQL Server Service – Find SQL Server Service – Properties – FILESTREAM – Allow remote clients to access FILESTREAM data as needed in the service list on the right Select, select both other recommendations. After the configuration is completed, you need to restart the SQL Server service for the settings to take effect.
Then use the following script to create the test database and test table
-- =========================================================-- 启用 filestream_access_level-- =========================================================EXEC sp_configure 'filestream_access_level', 2; -- 0=禁用 1=针对 T-SQL 访问启用 FILESTREAM 2=针对 T-SQL 和 WIN32 流访问启用 FILESTREAMRECONFIGURE;
GO-- =========================================================-- 创建测试数据库-- =========================================================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-- =========================================================-- =================================================-- 创建 包含 FileStream 数据的表-- -------------------------------------------------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 脚本实现带进度显示的文件存(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("将文件保存到 FileStream")
Write(sqlConnection, "test", "f:\temp\re.csv")
Console.WriteLine("从 FileStream 读取数据保存到文件")
Read(sqlConnection, "test", "f:\temp\re_1.csv")
Catch ex As System.Exception
Console.WriteLine(ex.ToString())
Finally
sqlConnection.Close() End Try
Console.WriteLine("处理结束，按 Enter 退出")
Console.ReadLine() End Sub ''' <summary>
''' 将文件保存到数据库 ''' </summary>
''' <param name="conn">数据库连接</param> ''' <param name="name">名称</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 '事务
Dim transaction As SqlTransaction = conn.BeginTransaction("mainTranaction")
sqlCmd.Transaction = transaction
'1. 读取 FILESTREAM 文件路径 ( 注意函数大小写 )
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. 读取当前事务上下文
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. 获取 Win32 句柄，并使用该句柄在 FILESTREAM BLOB 中读取和写入数据 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>
''' 从数据库读取数据保存到文件 ''' </summary>
''' <param name="conn">数据库连接</param> ''' <param name="name">名称</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. 读取 FILESTREAM 文件路径 ( 注意函数大小写 )
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. 读取当前事务上下文
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. 获取 Win32 句柄，并使用该句柄在 FILESTREAM BLOB 中读取和写入数据
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 ModuleThis article explains how to access SQL Server FileStream with progress. For more related content, please pay attention to the php Chinese website.
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