depends on how you connect your report to the data. If you are using a ODBC driver, if the driver exists CR probably supports it. If you use an application, the application can gather the data and push it to CR, in which any database is available.
It would be easier to ask for what you want, as there are many systems database systems out there that no one has heard of, but some one is using, so a complete list is probably not feasible.