bak db in local ?

I guess it really depends on what you're trying to do? If you need to perform some major changes to the production database, I suggest you back it up through the Control Panel, download it, and then restore it locally to work on it. Then make a backup locally, upload it, and restore it to your production database (assuming you account for any database updates in between that time). Otherwise, if it's minor changes, make the alterations locally using T-SQL to ensure the changes are what you want, and then run the scripts against the production database when you're ready.