oracle如何创建一个只读用户，该只读用户可以查看所有人的表及视图权限，查询数据字典的权限，但不能创建表、索引、插入、更新、删除数据

1.创建角色

CREATE ROLE SELECT_ROLE

2.给角色分配权限

grant create session TO SELECT_ROLE;

grant SELECT ANY DICTIONARY to SELECT_ROLE;

grant SELECT ANY TABLE to SELECT_ROLE;

grant SELECT ANY TRANSACTION to SELECT_ROLE;

grant SELECT ANY SEQUENCE to SELECT_ROLE