You can press the letter 'c' in top to toggle between "command line" and "program name".
A CPU usage of 99 % is not necessarily a problem. If a system has resources available it would be foolish not to allocate all available resources to a process that demands it. If the general system response is slow, you have a problem with a bad process or hardware error that prevents proper resource allocation, or your system does not have the appropriate hardware or configuration to efficiently handle the requested tasks.
If you want to know what an oracle user or Oracle Database is doing, you need to check this from within the Oracle database.