Getting Started with the SQL Server CLR

Summary

In this video, Michael OD, a SolarWinds contributor and CTO of Teek Inc., introduces the SQL Server CLR (Common Language Runtime), explaining its integration with the .NET Framework. He covers the benefits of SQL CLR, including enhanced string manipulation and external resource access, and walks through the process of creating and deploying SQL CLR objects such as stored procedures and user-defined functions. The video also addresses security considerations and offers a step-by-step guide to enabling and using SQL CLR objects in SQL Server, making complex tasks more efficient while maintaining system integrity.

Takeaways

• 😀 SQL Server CLR (Common Language Runtime) integrates the .NET Framework with SQL Server, allowing .NET code execution inside SQL Server.
• 😀 CLR was first introduced with SQL Server 2005 and enables SQL Server to utilize .NET classes and functionality, such as advanced string handling and external resource access.
• 😀 By using SQL Server CLR, developers can write stored procedures, user-defined functions, triggers, aggregates, and user-defined types with .NET languages like C#.
• 😀 The main advantage of SQL Server CLR is its ability to perform complex operations that T-SQL can't, such as regular expressions and handling larger datasets efficiently.
• 😀 One of the concerns with SQL Server CLR is the potential for security risks, as it allows external .NET code to run within SQL Server.
• 😀 Administrators can mitigate security concerns by setting appropriate permission levels, such as the 'SAFE' permission set, to limit access to external resources.
• 😀 Enabling SQL Server CLR involves using the `sp_configure` command to turn on CLR functionality, which is disabled by default.
• 😀 After enabling CLR, the process involves creating a .NET DLL (typically with Visual Studio), deploying the DLL as an assembly to SQL Server, and creating SQL CLR objects like stored procedures.
• 😀 The creation of SQL CLR objects can be done manually by first creating a DLL, then using the `CREATE ASSEMBLY` and `CREATE PROCEDURE` SQL commands to deploy and reference the code in SQL Server.
• 😀 Once deployed, executing a SQL CLR stored procedure is identical to executing a standard T-SQL stored procedure in SQL Server Management Studio (SSMS).
• 😀 The flexibility provided by SQL Server CLR enables developers to create more powerful and complex database solutions, though it requires careful attention to security settings.

Q & A

What is SQL Server CLR and how does it integrate with SQL Server?

SQL Server CLR (Common Language Runtime) is the integration of the .NET Framework with the SQL Server relational database engine. It allows developers to leverage the .NET Framework's classes and functionality within SQL Server, enabling features like advanced string manipulation, regular expressions, and external resource access in stored procedures, user-defined functions, triggers, and more.

What are the primary advantages of using SQL Server CLR?

SQL Server CLR offers several advantages, including better support for complex data processing tasks, such as handling strings and performing regular expressions. It also allows SQL Server to interact with external resources, which is not possible with T-SQL alone. CLR can extend SQL Server's capabilities by providing access to the rich class library of the .NET Framework.

Why might some administrators be cautious about enabling SQL Server CLR?

Some administrators are concerned about the security implications of enabling SQL Server CLR. CLR objects allow external code execution within SQL Server, which can introduce potential risks, such as unauthorized access to internal memory or external resources. However, these concerns can be mitigated by using appropriate security settings when creating CLR objects.

How do you enable SQL Server CLR?

To enable SQL Server CLR, you need to run the following commands in SQL Server Management Studio (SSMS): `EXEC sp_configure 'clr enabled', 1; RECONFIGURE;`. This will activate CLR support, allowing you to use CLR objects in SQL Server.

What steps are involved in creating a SQL CLR stored procedure?

The process of creating a SQL CLR stored procedure involves several steps: 1) Enable CLR in SQL Server, 2) Create a .NET DLL using Visual Studio with the necessary code for the stored procedure, 3) Deploy the DLL by creating an assembly in SQL Server, and 4) Create the stored procedure that references the assembly and executes the CLR code.

What tools are used to create a .NET DLL for SQL Server CLR?

You can use Visual Studio to create a .NET DLL for SQL Server CLR. The Visual Studio 2015 Community Edition is free and provides templates specifically designed for creating SQL CLR objects. It automatically includes the required namespaces and simplifies the creation of the necessary code.

What is the role of the `CREATE ASSEMBLY` statement in SQL Server CLR?

The `CREATE ASSEMBLY` statement is used to deploy the .NET DLL in SQL Server. It specifies the location of the DLL file and the permission set for the assembly. Once the assembly is created, you can use it to create SQL CLR objects such as stored procedures, functions, or triggers.

What are the different permission sets available for SQL Server CLR objects, and what do they mean?

There are three permission sets for SQL Server CLR objects: 1) `SAFE` – The CLR object cannot access external resources or SQL Server's internal memory. 2) `EXTERNAL_ACCESS` – The CLR object can access external resources like file systems or network resources. 3) `UNSAFE` – The CLR object has unrestricted access to external resources and memory, but this setting should be used with caution due to potential security risks.

How do you execute a SQL CLR stored procedure in SQL Server?

Executing a SQL CLR stored procedure is identical to executing a standard T-SQL stored procedure. You use the `EXEC` command in SQL Server Management Studio (SSMS), for example: `EXEC usp_MySQLCLR;`. This will run the procedure, and the output will be displayed in the results window.

Can SQL Server CLR objects be created in languages other than C#?

Yes, SQL Server CLR objects can be created using any .NET language, such as C#, VB.NET, or F#. The .NET language you choose will determine the syntax and features you can use, but the process of creating CLR objects in SQL Server remains the same.