如何查看oracle用户具有的权限和角色

查看用户或角色系统权限
select * from dba_sys_privs;
select * from user_sys_privs;
查看用户对象权限
select * from dba_tab_privs;
select * from all_tab_privs;
select * from user_tab_privs;
查看所有角色
select * from dba_roles;
查看用户或角色所拥有的角色：
select * from dba_role_privs;
select * from user_role_privs;