--当前的连接数

select count(*) from v$session;

--数据库允许的最大连接数

select value from v$parameter where name = 'processes';

--并发连接数

Select count(*) from v$session where status='ACTIVE';

--查看不同用户的连接数

select username,count(username) from v$session where username is not null group by username;

--并发连接数

select count(*) from v$session where status='ACTIVE'　;

--查看当前有哪些用户正在使用数据

SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machine

from v$session a, v$sqlarea b

where a.sql_address =b.address

--and a.username = 'SYS'

order by cpu_time/executions desc;

--查询是否有死锁

select * from v$locked_object;