?????????????
???????Scott???????????owner??emp???Scott???????????????????
????a:????????????????with  grant  option
????grant select on owner.emp to scott with grant option;
????b:?????????? with admin option
????grant connect to  scott with admin option; //scott???????????????′???
??????owner——>scott——>xiaoming??owner??scott?????????????????xiaoming???????????????xiaoming ???????????????????????????~
???????????
??????profile???????????
??????1???????????
????create  profile   lock_account  limit  failed_login_attempts 3 password_lock_time 2; //????profile???  ??2??????????????
????alter user  xiaoming   profile   lock_accout;  //????????????xiaoming
??????2?????????????(dba???)
????alter user  tea  accont  unlock;
??????3?????????dba????
????create profile  myprofile  limit  password_life_time  10  password_grace_time  2??//???10?????????????????????2??
????alter  user  tea  profile  myprofile//?????????????xx
??????4??????????????????????????????????ù???????
????create  profile  password_history  limit password_life_time 10  password_grace_time 2 password_reuse_time 10
????password_reuse_time  //???????????????????10??????????
????????????
??????5?????profile
????drop  profile  password_history  [cascade]????????????????????