The common language runtime (CLR) is the heart of the Microsoft .NET Framework and provides the execution environment for all .NET Framework code. Code that runs within the CLR is referred to as managed code. The CLR provides various functions and services required for program execution, including just-in-time (JIT) compilation, allocating and managing memory, enforcing type safety, exception handling, thread management, and security.
.With the CLR hosted in Microsoft SQL Server (called CLR integration), you can author stored procedures, triggers, user-defined functions, user-defined types, and user-defined aggregates in managed code. Because managed code compiles to native code prior to execution, you can achieve significant performance increases in some scenarios.
.CLR is faster than T-SQL in many cases. CLR is mainly used to accomplish task which are not possible by T-SQL or can use lots of resources. CLR can be usually implemented where there is intense string operation, thread management or iteration methods which can be complicated for T-SQL. Implementing CLR provides more security to Extended Stored Procedure.
.When writing stored procedures, triggers, and user-defined functions, one decision you must make is whether to use traditional Transact-SQL, or a .NET Framework language such as Visual Basic .NET or Visual C#. Use Transact-SQL for data access with little or no procedural logic. Use managed code for CPU-intensive functions and procedures that feature complex logic.
.To use the .Net DLLs in SQL, First we need to create a DLL using visual studio.net, then Enabling CLR Integration for database, then register the assembly using ‘Create Assembly’ key word after that you can use this assembly.