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Installation

Requirements​

  • SQL Server 2012 or later (2017+ recommended; note the CLR strict security changes it introduced). CLR integration is included in every edition, including Express.
  • .NET Framework SDK / Visual Studio with the SQL Server Data Tools (SSDT) workload, or the Microsoft.SqlServer.Server reference for plain class libraries.
  • Permission to run sp_configure and CREATE ASSEMBLY on the target instance (ALTER SETTINGS and CREATE ASSEMBLY permissions, typically sysadmin in development).

Enable CLR on the instance​

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

Verify:

SELECT name, value_in_use
FROM sys.configurations
WHERE name IN ('clr enabled', 'clr strict security');

Project setup​

Option A — SSDT database project (recommended)​

  1. Create a SQL Server Database Project in Visual Studio.
  2. Add a SQLCLR item (function, stored procedure, aggregate, or type).
  3. Set the target platform to match your SQL Server version.
  4. Publish — SSDT generates the CREATE ASSEMBLY and wrapper DDL for you.

Option B — plain class library​

  1. Create a .NET Framework class library (match the CLR version your SQL Server hosts — CLR 4 for SQL Server 2012+).
  2. Reference System.Data and use the Microsoft.SqlServer.Server namespace attributes.
  3. Deploy by hand with CREATE ASSEMBLY as shown in the Quick Start.
note

SQL Server hosts the .NET Framework runtime. Assemblies targeting .NET Core / .NET 5+ cannot be loaded by CLR integration.

Verify the install​

SELECT * FROM sys.assemblies WHERE is_user_defined = 1;
SELECT * FROM sys.assembly_modules;

If your assembly and its modules appear, you're ready for the Examples.