--Check if CLR is enabled
select * from sys.configurations where name = 'clr enabled'

-- Turn advanced options on
EXEC sp_configure 'show advanced options' , '1';
GO
RECONFIGURE;
GO
-- Enable CLR
EXEC sp_configure 'clr enabled' , '1'
GO
RECONFIGURE;
GO
-- Turn advanced options back off
EXEC sp_configure 'show advanced options' , '0';
GO
RECONFIGURE;
GO

-- Determine database compatiblity level
exec sp_helpdb 'YourDatabaseName'

-- If compatibility_level less than 90
ALTER DATABASE YourDatabaseName SET SINGLE_USER
GO
EXEC sp_dbcmptlevel YourDatabaseName, 90;
GO
ALTER DATABASE YourDatabaseName SET MULTI_USER
GO