Managing users
1.create a user: database authentication
sql> create user juncky identified by oracle default tablespace users
temporary tablespace temp quota 10m on data
password expire
[account lock|unlock]
[profile profilename|default];
2.change user quota on tablespace
sql> alter user juncky quota 0 on users;
#0 代表以后不能再新增对像,之前已经建好的还将保留
3.drop a user
sql> drop user juncky [cascade];
#[cascade],删除与用户相关的所有对像，如table, index,trriger
#如果当前用户正连接在oracle上，是不能够被删除的。
4. monitor user
view: dba_users , dba_ts_quotas