Drop database; SQL*Plus command

This command was introduced in Oracle10g and is very efficient.
The command will clean up all datafiles, online redo log files, controlfiles and spfile. It will not touch pfile & password file. On windows server, the service need to be deleted manually.
In case, one wants to remove archivelogs & backups execute this command from RMAN using the 'Including backups' option.
Word of caution here:::All RMAN backups associated with target database will be deleted from all configured device types.
Steps:

shutdown abort;  
startup mount exclusive restrict;   
drop database;  

Oracle mentions in it's document... that user must have SYSDBA system privilege to issue this statement. The database must be mounted in exclusive and restricted mode, and it must be closed.

Link::

http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/statements_8009.htm#i215798

Performance statistics of database

Interestingly, maybe not surprisingly, we tend to let certain things go in background since, we are not using/doing that action as part of our daily work .I am grateful to Syed who pushed me to move from my comfort zone.
Preserving performance data in different Oracle versions...
Oracle 9i=> Performance statistics of a database was generally created in perfstat schema. So all we had to do was export user perfstat data and this dumpfile could be used for importing in another database in case required for analysis.
Oracle 10g=> introduced a few new reports and performance statistics was by default enabled to take snapshots every hour. Automatic Workload Repository (AWR) for cumulative and delta values at all levels except session & active session history (ASH) for the current state of all active sessions. By default we have snapshots of the performance data once every hour and the statistics are retained in the workload repository for 7 days.
To preserve this performance data, we gotta use "awrextr.sql" script to extract data into a data pump export file and "awrload.sql" script to load this data from dump file.
Oracle 11g=> The same system holds. A few enhancements are of course seen. So, to preserve this Oracle database performance data, we gotta use "awrextr.sql" script to extract data into a data pump export file and "awrload.sql" script to load this data from dump file.