Oracle Memory Tunning

Licensing:
select* from v$versions
select * from v$license;

SGA Info:

show sga

select * from v$sga;

select * from v$sgainfo;

select * from v$sgastat;

Explain plan:

set autotrace traceonly explain
select ename from emp where empno = 12;

For more Info:

http://www.datadisk.co.uk/html_docs/oracle/db_control.htm