Which version of sql server 2008 is free?

1, all versions are free, provided that they cannot be used for production.

2.Express version is a stand-alone version in principle, and there is no serial number limit. So, in principle, it is free. However, such a version cannot be used for production.

3. All versions can find available serial numbers on the Internet. When installing and using, there is no need for authentication, activation and other links except entering the serial number. However, if a regular enterprise uses it for production without authorization, it may be sued for infringement.

4. There is no need to mention anything about personal study and testing.