创建测试用户a并在a中创建t1,t2两个测试表,另外创建用户b(只授权登录权限)

[oracle@xifenfei ~]$ ss

SQL*Plus: Release 23.0.0.0.0 - for Oracle Cloud and Engineered Systems on Mon Jul 29 22:14:11 2024
Version 23.5.0.24.07

Copyright (c) 1982, 2024, Oracle.  All rights reserved.


Connected to:
Oracle Database 23ai Enterprise Edition Release 23.0.0.0.0 - for Oracle Cloud and Engineered Systems
Version 23.5.0.24.07

SQL> show pdbs;

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         3 XIFENFEI                       READ WRITE NO

SQL> create user b identified by oracle;

User created.

SQL> grant create session  to b;

Grant succeeded.

SQL> grant unlimited tablespace to a;

Grant succeeded.

SQL> create table a.t1 as select * from dba_objects;

Table created.

SQL> c/t1/t2;
  1* create table a.t2 as select * from dba_objects
SQL> /

Table created.

SQL> select count(1) from a.t1;

  COUNT(1)
----------
     70638

SQL> select count(1) from a.t2;

  COUNT(1)
----------
     70639

SQL> create user b identified by oracle;

User created.

SQL> grant create session  to b;

Grant succeeded.

直接使用b用户登录并尝试查询a用户数据,结果是无法查询数据报ora-00942(意料之中因为b现在无权限访问a.t1表)

SQL> conn b/oracle@127.0.0.1/xifenfei
Connected.
SQL> select count(1) from a.t1;
select count(1) from a.t1
                       *
ERROR at line 1:
ORA-00942: table or view "A"."T1" does not exist
Help: https://docs.oracle.com/error-help/db/ora-00942/

直接schema级别授权a用户下面的表给b用户查询权限

[oracle@xifenfei ~]$ ss

SQL*Plus: Release 23.0.0.0.0 - for Oracle Cloud and Engineered Systems on Mon Jul 29 22:07:14 2024
Version 23.5.0.24.07

Copyright (c) 1982, 2024, Oracle.  All rights reserved.


Connected to:
Oracle Database 23ai Enterprise Edition Release 23.0.0.0.0 - for Oracle Cloud and Engineered Systems
Version 23.5.0.24.07

SQL>  grant select any table on schema a to b;

Grant succeeded.

SQL>  conn b/oracle@127.0.0.1/xifenfei
Connected.
SQL> select count(1) from a.t1;

  COUNT(1)
----------
     70638

SQL> select count(1) from a.t2;

  COUNT(1)
----------
     70639

在a用户中新增加表,在b用户中可以直接查询(无需再次授权)

SQL> conn a/oracle@127.0.0.1/xifenfei
Connected.
SQL>  create table t3 as select * from tab;

Table created.

SQL> select count(1) from t3;

  COUNT(1)
----------
         3

SQL> conn b/oracle@127.0.0.1/xifenfei
Connected.
SQL> select count(1) from a.t3;

  COUNT(1)
----------
         3

Oracle 23ai中，Oracle引入了架构级（SCHEMA级别）授权。这允许你以更简单、更直观的方式对整个Schema进行授权。以前的版本中如果需要类似授权操作,需要对schema下面所有表进行grant select on user.table to user2形式授权工作量比较大而且user1中如果新增加表还需要额外授权