Oracle SQLPlus是Oracle数据库的一种命令行工具，可以通过以下几种方式来监控数据库性能：
SELECT sid, serial#, username, program, action, state
FROM v$session;
SELECT * FROM v$sysstat WHERE name IN ('CPU used by this session', 'physical reads', 'physical writes');
SELECT sql_id, executions, parse_calls, buffer_gets, disk_reads, sql_text
FROM v$sql
ORDER BY executions DESC;
SELECT event, total_waits, total_timeouts, time_waited
FROM v$system_event
ORDER BY time_waited DESC;
通过以上方式，可以使用Oracle SQLPlus监控数据库性能，及时发现潜在的性能问题，并进行调优。
