Can defragger be used to defrag an SQL server Database file whilst it is in use?
I believe that it can, since it uses Windows API hooks.
this is just an educated guess, but i'd would have said No, you can't defrag a database that is in production.
which is why they have maintenace windows where they close the database, defrag, and restart.
but i'm no expert on SQL so happy to be proven wrong.