Common authority query instructions in Oracle

Introduce ：

-- Permissions are divided into system permissions and object permissions , A role is a collection of permissions . System permission is right Oracle Operation permission of , If connected , to grant authorization , establish create. Object permission is the operation permission of an object , Such as query . to update , Delete delete etc. .

-- View all users in the system , Both instructions work
select * from dba_users;  
select * from all_users; 

-- View the current user
select * from user_users;

-- View the roles of the current user
select * from user_role_privs;  

-- Check the roles in the system
select * from dba_roles;  

-- Check the roles of all users in the system
select * from dba_role_privs;

-- View with sysdba、sysoper、sysasm Users of roles
select * from  v$pwfile_users;

-- Check what permissions each role has
select * from role_sys_privs where role='DBA';

-- View the permissions of the current user
select * from dba_sys_privs where grantee='SYS';

-- View the permissions of the current user in different objects ,grantee Fields represent objects , An object is a specific data table or database or a stored procedure , Both instructions can be used
select * from dba_tab_privs;
select * from all_tab_privs;