Increase tablespace size

Hi,
I need to increase the tablespace size for SYSTEM/TEMP and user defined tablesspaces. I have 2 options
1) Adding one more datafile to tablespace with ALTER TABLESPACE command 2) Increasing size of existing database file size with ALTER DATABASE command.

which option is better?

Is it possible to run these commands when database is open.

Thanks Received on Fri Aug 26 2005 - 14:59:14 CDT