Common Language Runtime

 

The CLR process provides communications to .NET libraries. This is a new feature in SQL Server 2005 and allows developers to extend the power of the database engine by writing high-level code that can be called inside T-SQL just like a stored procedure or a function. Developers compile the code and then instantiate it into the database, or they can use Visual Studio to develop and instantiate the assembly directly into the database.

This ability is both a blessing and a curse. Providing a high-level language processor gives an incredible amount of flexibility to the platform, but also allows for poorly written code to disappear into a black box. Great care should be taken in implementing this feature.

The CLR has proven to be very stable, so it will not easily crash your SQL Server. Because of the security implications, however, you have to enable the CLR on a SQL Server before the developers can instantiate any assemblies into the database. To do that, you can use the SQL Server Surface Area Configuration (SAC) tool, or run the following statements on SQL Server 2005:

EXEC sp_configure 'show advanced options', '1';
GO
RECONFIGURE;
GO
EXEC sp_configure 'clr enabled', '1'
GO
RECONFIGURE;