创建用户:
create user isc identified by "isc"  default tablespace USERS temporary tablespace TEMP profile DEFAULT;
grant connect to isc;
grant dba to isc;
grant resource to isc;
grant unlimited tablespace to isc;
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更改用户名密码:　
alter user isc identified by password
或者:
connect isc/abc123
输入:password
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删除用户
Connect system/admin
Drop user username；

为用户授予角色
Grant dba to isc；
Grant connect to isc；