The ALTER ASSEMBLY statement in SQL Server is used to modify an existing assembly that has been registered in the SQL Server database. This can include tasks such as adding new versions, updating existing assemblies, or changing their properties. Here’s how you can use the ALTER ASSEMBLY statement effectively.
Basic Syntax
The basic syntax for the ALTER ASSEMBLY statement is as follows:
ALTER ASSEMBLY assembly_name
[WITH ( option_list )]
[FROM 'path_to_assembly']
Components of the Syntax
- assembly_name: The name of the existing assembly you want to alter.
- WITH ( option_list ): Additional options for modifying the assembly, like specifying a new permission set.
- FROM 'path_to_assembly': The path to the new assembly file if you want to replace the existing assembly with a new version.
Example Usage
1. Updating an Existing Assembly:
If you want to update a previously registered assembly with a new file, you can do this with the FROM clause:
ALTER ASSEMBLY MyAssembly
FROM 'C:\Path\To\New\MyAssembly.dll'
This command will replace the existing MyAssembly with the new one located at the specified path.
2. Changing the Permission Set:
You can also modify the permission set of an existing assembly by using the WITH clause:
ALTER ASSEMBLY MyAssembly
WITH PERMISSION_SET = SAFE
This changes the permission set of MyAssembly to SAFE.
Important Considerations
- Permissions: To alter an assembly, you typically need the ALTER permission on the assembly.
- Dependencies: Ensure that there are no active sessions or dependencies on the assembly when you attempt to modify it.
- Transactions: Consider wrapping the command in a transaction if the changes are critical and should be rolled back in case of failure.
Summary
The ALTER ASSEMBLY statement is a powerful tool for managing .NET assemblies within SQL Server. It allows you to update assemblies, modify their permissions, and ensure that your database applications remain functional and secure. Always ensure backups are in place before making changes to assemblies in a production environment.