32.choose the best answer

View the Exhibit and examine the data in EMP and DEPT tables.

In the DEPT table, DEPTNO is the PRIMARY KEY.

In the EMP table, EMPNO is the PRIMARY KEY and DEPTNO is the FOREIGN KEY referencing

the DEPTNO column in the DEPT table.

What would be the outcome of the following statements executed in the given sequence?

DROP TABLE emp;

FLASHBACK TABLE emp TO BEFORE DROP;

INSERT INTO emp VALUES (2,'SCOTT', 10);

INSERT INTO emp VALUES (3,'KING', 55);

A) Both the INSERT statements would succeed because none of the constraints on the table are automatically retrieved when the table is flashed back.

B) Only the second INSERT statement would succeed because all the constraints except referential integrity constraints that reference other tables are retrieved automatically after the table is flashed back.

C) Both the INSERT statements would fail because all constraints are automatically retrieved when the table is flashed back.

D) Only the first INSERT statement would succeed because all the constraints except the primary key constraint are automatically retrieved after a table is flashed back.

Answer:B

(解析:除了引用其他表的引用完整性约束之外,所有约束在表被闪回之后自动恢复,已经做过实验)

最新文章

  1. 【转】基于 CoreText 实现的高性能 UITableView
  2. innodb insert buffer 插入缓冲区的理解
  3. mvc与三层结构终极区别
  4. 年前辞职-WCF入门(6)
  5. PMP考试--价值工程法
  6. JAVA大数类练手
  7. jQuery Ajax(load,post,get,ajax)用法与详解
  8. ios中从相册:相机中获取图片信息
  9. HDU2149-Public Sale
  10. [转]浅谈PCA的适用范围
  11. 老男孩Python全栈开发(92天全)视频教程 自学笔记16
  12. UNIX环境高级编程——线程同步之读写锁以及属性
  13. BZOJ_3555_[Ctsc2014]企鹅QQ_哈希
  14. 英语口语练习系列-C19-喜欢某人
  15. CSS 实现隐藏滚动条同时又可以滚动
  16. 4.ClassLink - 一种新型的VPC 经典网络的连接方式
  17. java 线程Thread 技术--1.5Lock 与condition 演示生产者与消费模式
  18. TAC队--团队选题报告
  19. 两台Linux主机互传文件可以使用SCP命令来实现
  20. cmd enabledelayedexpansion

热门文章

  1. uvalive 7299 Boggle
  2. go_接口
  3. 技术讨论]mongodb驱动的正确使用方法
  4. qt QTcpServer与QTcpSocket通讯
  5. 如何使用vsphere client 克隆虚拟机
  6. ie7下 li多了4像素
  7. HTTP 499 状态码 nginx下 499错误
  8. windows7文件夹怎样默认图片大图显示?
  9. java try catch finally return执行
  10. OpenGL中的像素包装理解