Large Object (LOB) Handling

Artikel
12/03/2008

The HandlingLOBUsingCLR sample for SQL Server 2005 demonstrates transferring large objects (LOBs) between SQL Server and a file system that is available to the server by using common language runtime (CLR) stored procedures. This sample demonstrates how to access files in server-side code, and then invoke both dynamic queries and stored procedures from CLR-based stored procedures. It also demonstrates how to unregister and register CLR methods and assemblies by using Transact-SQL.

The default installation directory is drive:\Program Files\Microsoft SQL Server\90\Samples\Engine\Programmability\CLR\HandlingLOBUsingCLR.

Scenario

A developer wants to copy images between SQL Server and the file system on the server.

Languages

Transact-SQL, Visual C#, and Visual Basic.

Features

The HandlingLOBUsingCLR sample uses the following features of SQL Server:

Application Area	Features
Overall	CLR stored procedures; calling Transact-SQL stored procedures from CLR stored procedures; the VARBINARY(MAX) data type.

Prerequisites

Before running this sample, make sure the following software is installed:

SQL Server 2005 or SQL Server 2005 Express Edition (SQL Server Express). You can obtain SQL Server Express free of charge from the SQL Server 2005 Express Edition Documentation and Samples Web site
The AdventureWorks database which is included with SQL Server 2005, and is also available at the SQL Server Developer Web site.
The SQL Server 2005 Database Engine samples. These samples are included with SQL Server 2005. You can download the latest version of the samples at the SQL Server Developer Web site.
.NET Framework SDK 2.0 or Microsoft Visual Studio 2005. You can obtain .NET Framework SDK free of charge. See Installing the .NET Framework SDK.

Building the Sample

If you have not already created the strong-name key file ExternalSampleKey.snk, generate the key file using the following instructions.

To generate a strong name key file

Open a Microsoft Visual Studio 2005 command prompt. Click Start, point to All Programs, point to Microsoft Visual Studio 2005, point to Visual Studio Tools, and then click Visual Studio 2005 Command Prompt.

—Or—

Open a Microsoft .NET Framework command prompt. Click Start, point to All Programs, point to Microsoft .NET Framework SDK 2.0, and then click SDK Command Prompt.
At the command prompt, use the change directory (CD) command to change the current folder of the command prompt window to the Samples folder.

Note

To determine the folder where samples are located, click Start, point to All Programs, point to Microsoft SQL Server 2005, point to Documentation and Tutorials, and then click Samples Directory. If the default installation location was used, the samples are located in <system_drive>:\Program Files\Microsoft SQL Server\90\Samples.
At the command prompt, run the following command to generate the key file:

sn -k ExternalSampleKey.snk

Important

For more information about the strong-name key pair, see "Security Briefs: Strong Names and Security in the .NET Framework" in the .NET Development Center on MSDN.

To build the sample, do the following:

Build the sample

Compile the sample by using Visual Studio 2005 and the provided Visual Studio solution, or by using Microsoft MSBuild, which is included in the .NET Framework SDK 2.0. Run a command similar to the following at the command prompt:

msbuild /nologo /verbosity:quiet /property:Configuration=Debug CS\HandlingLOBUsingCLR.sln
Make sure that the AdventureWorks database is installed.
If you did not install the SQL Server Database Engine samples in the default location, modify the path in the CREATE ASSEMBLY part of the script in Scripts\InstallCS.sql and Scripts\InstallVB.sql to refer to location where the samples were installed.
If you are not an administrator for the SQL Server instance you are using, you must have an administrator grant you CreateAssembly permission to complete the installation.
Open the scripts\installCS.sql or scripts\installVB.sql file, depending on whether you compiled the Visual C# project or the Visual Basic project, in SQL Server Management Studio. Run the script that is contained in the file, or run a command similar to the following at the command prompt:

sqlcmd -E -I -i Scripts\InstallCS.sql

This script does the following:

Running the Sample

To run the sample, do the following:

Run the sample

To read an image from the database, invoke a script similar to the following:

exec GetPhotoFromDB 70, 'C:\Temp\', 'test6.gif'

go

Make sure the directory you specify exists.
To write an image into the database, invoke a script similar to the following:

exec PutPhotoIntoDB 70, 'C:\Temp\', 'test1.gif'

go

Any errors will be reported to the error.log file in the directory that you specify. For scripts that are similar to the ones in this procedure, see the Scripts\test.sql file.

Removing the Sample

To remove the sample, do the following:

Remove the sample

Open the scripts\cleanup.sql file in Management Studio and run the script that is contained in the file. Or, run the following command at the command prompt:

sqlcmd -E -I -i Scripts\cleanup.sql

Comments

The CLR for SQL Server 2005 or SQL Server 2005 Express Edition must be enabled for this sample to work correctly.

Samples are provided for educational purposes only. They are not intended to be used in a production environment and have not been tested in a production environment. Microsoft does not provide technical support for these samples. Sample applications and assemblies should not be connected to or used with your production SQL Server database or your report server without the permission of the system administrator.

Change History

Release	History
5 December 2005	Changed content: Changed instructions for generating a key file, including the name and location of the key file.

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