create table a(id int, name varchar(10))
go

create trigger a_update on a
for update
as
begin
	set nocount on	

	if @@rowcount = 0 return
	
	if exists(select 1 from inserted i join deleted d on i.id = d.id and i.name <> d.name)
		begin
			raiserror('abort update', 16, 1)
			rollback transaction
			return
		end
end
go

insert into a(id, name) values(1,'a')
go
update a set name = 'b' where id = 1
go
drop table a
go

IF NOT EXISTS (SELECT 1 FROM INSERTED) RETURN;