1.linux下修改oracle数据库用户密码

切换到oracle 用户（linux上的用户）： su - oracle
使用sqlplus并以管理员的身份登录: sqlplus / as sysdba
alter user 数据库连接用户名 identified by 新密码; #直接生效

eg:

alter user mryx  identified by walibo;
sqlplus mryx/walibo      #登录

2.解锁

alter user mryx  identified by  walibo  account  unlock;    #解锁

3.查某个用户的生命周期限定  默认180天

SELECT LIMIT FROM dba_profiles s where s.profile =( SELECT PROFILE FROM dba_users where USERNAME=‘用户名‘) and RESOURCE_NAME=‘PASSWORD_LIFE_TIME‘ ;
SELECT LIMIT FROM dba_profiles s where s.profile =( SELECT PROFILE FROM dba_users where USERNAME=‘mryx‘) and RESOURCE_NAME=‘PASSWORD_LIFE_TIME‘ ;
SELECT LIMIT FROM dba_profiles s where s.profile =( SELECT PROFILE FROM dba_users where USERNAME=‘SYSTEM‘) and RESOURCE_NAME=‘PASSWORD_LIFE_TIME‘ ;

 4.可查看是否有服务连着数据库

select machine,client_info,program from gv$session where username is not null group by inst_id,machine,program order by machine DESC;