SQL Server 2008中使用FileStream存取大文件的相关知识是本文我们主要要介绍的内容,我们知道,SQL Server 2008中引入了Filestream,使用它可以将非机构化大型数据(如文本文档、图像和视频)等以varbinary(max)的形式存储在文件系统中。使用数据库的备份还原功能可以将这些数据一起备份还原。本文将简单总结如何创建可以使用FileStream的数据库以及如何使用c#访问存取数据。

1. 创建数据库
创建数据时可以执行以下T-SQL语句,
- CREATE DATABASE TestDB
 - ON
 - PRIMARY ( NAME = TestDB,
 - FILENAME = 'c:\data\TestDB.mdf'),
 - FILEGROUP FileStreamGroup1 CONTAINS FILESTREAM( NAME = Arch3,
 - FILENAME = 'c:\data\filestream1')
 - LOG ON ( NAME = TestDBlog,
 - FILENAME = 'c:\data\TestDBlog.ldf')
 - GO
 
如果是在已经创建好的数据库上启用FileStream,可以
- a. Right click the “TestDB” database and select “Properties”.
 - b. First create a FileGroup, click “Filegroups” menu and create one under “Stream” section,
 - named “FileStreamGroup1”. And then click “Files” menu, and add a file named “filestream1”
 - and Set it’s FileGroup to “FileStreamGroup1”, and then specify a folder to hold data,
 - like c:\Data. Click ok, and you can check the folder “c:\data” to see what is added.
 
2. 创建表
- CREATE TABLE [dbo].[TestTable2](
 - [ID] [uniqueidentifier] ROWGUIDCOL NOT NULL,
 - [ContentType] [nvarchar](50) NOT NULL,
 - [FileName] [nvarchar](50) NOT NULL,
 - [FileContent] [varbinary](max) FILESTREAM NULL,
 - [FileSize] [int] NULL,
 - CONSTRAINT [PK_TestTable2] PRIMARY KEY CLUSTERED
 - (
 - [ID] ASC
 - )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,
 - ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] FILESTREAM_ON [FileStreamGroup1]
 - ) ON [PRIMARY] FILESTREAM_ON [FileStreamGroup1]
 - GO
 - SET ANSI_PADDING OFF
 - GO
 
如果表已经创建,可以执行以下TSQL来设置:
- ALTER TABLE [dbo].[TestTable] alter column ID [uniqueidentifier] not null
 - ALTER TABLE [dbo].[TestTable] alter column ID add ROWGUIDCOL
 - ALTER TABLE [dbo].[TestTable] add FileContent varbinary(MAX) FILESTREAM;
 
3. 使用C#读写
读:
- SqlConnection conn = null;conn = new SqlConnection(connect);
 - conn.Open();
 - tx = conn.BeginTransaction();var qry = "SELECT FileName, FileContent.PathName() as FilePath,
 - ContentType, GET_FILESTREAM_TRANSACTION_CONTEXT() as TranContext FROM TestTable2 WHERE ID = @ID";
 - var cmd = new SqlCommand(qry, conn, tx);
 - cmd.Parameters.AddWithValue("@ID", id);using (rdr = cmd.ExecuteReader())
 - { if (rdr.HasRows)
 - {
 - rdr.Read();
 - fileModel = new FileModel();
 - fileModel.FileName = Convert.ToString(rdr["FileName"]);
 - fileModel.FilePath = Convert.ToString(rdr["FilePath"]);
 - byte[] tranContext = (byte[])rdr["TranContext"];
 - fileModel.ContentType = Convert.ToString(rdr["ContentType"]); ;
 - fileModel.FileStream = new SqlFileStream(fileModel.FilePath, tranContext, FileAccess.Read);
 - }
 - }
 
得到文件的Stream,就可以对该文件进行读写操作了。
写:
- public static void PostFileToDB(HttpPostedFileBase file)
 - {
 - string fileName = Path.GetFileName(file.FileName);
 - string contentType = file.ContentType;
 - int filefileSize = file.ContentLength / 1024;
 - using (SqlConnection conn = new SqlConnection(connect))
 - {
 - conn.Open();
 - using (SqlTransaction trn = conn.BeginTransaction ())
 - {
 - SqlCommand cmdInsert = new SqlCommand(
 - @"insert into TestTable2
 - (FileName, FileContent, ContentType, FileSize)
 - output
 - INSERTED.FileContent.PathName(),
 - GET_FILESTREAM_TRANSACTION_CONTEXT ()
 - values
 - (@FileName, 0x, @ContentType, @FileSize)", conn, trn);
 - cmdInsert.Parameters.Add("@FileName", SqlDbType.VarChar, 256);
 - cmdInsert.Parameters["@FileName"].Value = fileName;
 - cmdInsert.Parameters.Add("@ContentType", SqlDbType.VarChar, 256);
 - cmdInsert.Parameters["@ContentType"].Value = contentType;
 - cmdInsert.Parameters.Add("@FileSize", SqlDbType.Int);
 - cmdInsert.Parameters["@FileSize"].Value = fileSize;
 - string path = null;
 - byte[] context = null;
 - // cmdInsert is an INSERT command that uses the OUTPUT clause
 - // Thus we use the ExecuteReader to get the
 - // result set from the output columns
 - // using (SqlDataReader rdr = cmdInsert.ExecuteReader())
 - {
 - rdr.Read();
 - path = rdr.GetString(0);
 - context = rdr.GetSqlBytes(1).Buffer;
 - }
 - using (SqlFileStream sfs = new SqlFileStream(
 - path, context, FileAccess.Write))
 - {
 - file.InputStream.CopyTo(sfs);
 - }
 - trn.Commit ();
 - }
 - }
 - }
 
关于SQL Server 2008中使用FileStream存取大文件实例就介绍到这里了,希望本次的介绍能够对您有所收获!
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