![](https://csdnimg.cn/release/download_crawler_static/86994135/bg6.jpg)
子查询的限制:不能使用ORDER BY子句 ................................................................................7
不相关子查询: .....................................................................................................................7
相关子查询: .........................................................................................................................7
一、带有IN谓词的子查询:此为不相关子查询 ..................................................................7
二、带有比较运算符的子查询..............................................................................................7
三、带有ANY(SOME)或ALL谓词的子查询 .......................................................................7
四、带有EXISTS谓词的子查询...............................................................................................7
4.1.2 安全标准简介:TCSEC标准、CC标准...................................................................................7
4.2.2 存取控制 ................................................................................................................................8
4.2.3 自主存取控制方法.................................................................................................................8
4.2.4 授权与回收 .............................................................................................................................8
1、WITH GRANT OPTION: 指定:可以再授予;没有指定:不能传播;不允许循环授权8
2、GRANT ALL PRIVILIGES.......................................................................................................8
3、 对属性列的授权时必须明确指出相应属性列名 ...........................................................8
1、 FROM USER CASCADE;系统收回直接或间接从USER处获得的权限 .....................8
4.2.5 数据库角色:是被命名的一组与数据库操作相关的权限,角色是权限的集合...............8
4.2.6 强制存取控制方法.................................................................................................................8
4.3 视图机制....................................................................................................................................9
4.4 审计(Audit)...........................................................................................................................9