Prevent UPDATE TRIGGER to fire when no changes made in SYBASE
I don't know SyBase but from the documentation, it appears as if you can check whether one or more columns are updated. It should be sufficient to check if one is updated like:

create trigger test_utrig on test 
for update as  
    if update (id)
        insert into audit..test_a (updated_by, date, Id, ,NAME, DESC)
        select update_by(), getdate(), inserted.Id, inserted.NAME, inserted.DESC 
        from inserted


It appears to be a mismatch between the number of columns in the trigger and in the audit table, so I removed the constant 'update'.