How to find number of files opened or open file descriptors allocated for a user.

1. How to find number of files opened up by a user.
    For example to find files opened by oracle: /usr/sbin/lsof | grep oracle | wc -l

2. How to find open file descriptors allocated for a user, example oracle user :
a. Search for the process and then do pick the process id.
b. Then cat /proc/<pid>/limits