im struggling with some viruses which corrupt windows files
In that case the very first thing you
MUST do is to reformat all affected computers. Things like DeepFreeze can help to prevent reinfection, but only if you can ensure it wasn't infected in the first place.
Assuming the virus wasn't powerful enough to tamper with the DeepFreeze image.
but does not harm the database on workstation.
You can never ensure that, once a virus entered your system, it can do whatever the user can, so if the user can read and write a database, so can the virus (wheter or not it really does, it depends on what is the exact malware, but you should never rely on this).
However, having a database on a workstation is a
terrible mistake, for more than security. For starters, you can't easily share it among users, which impedes teamwork, or need to share from a workstation, which complicates network configuraton.
But most important it prevents proper backups, as the IT staff won't go into each computer to backup what's important there. Also, there is the security issue of the computer becoming compromised, and the user having full access to take the DB with him if he really wants.
Generally speaking, it's often said that the only important thing in the network are the servers, so that's where all the attention should go. Any data on workstations is considered temporary and unimportant, so it's not cared for. That's why databases and important files are ons propertly secured servers.
On the other hand I have seen that deepfreeze has an app for servers, I was thinking of leaving the database in the thawed area.
DeepFreeze is not a good idea for servers (and I can't think why they need a different program at all). Servers aren't public untrusted places, but controled work areas with secured systems in them. There is little need for it, as any change made was made by an administrator or a properly autorized user. Normal backups cover accidental damage or a virus infection.