> GDSException: org.firebirdsql.gds.GDSException: Dynamic SQL Error
> SQL error code = -901 feature is not supported

Can you post at least your select statement here? Also, it would be
great if you can create a test case that reproduces this error. This
error was posted here once, but I was not able to find the reason.

Also, can you try to execute same select statement in isql?

Best regards,
Roman Rokytskyy