问题
单项选择题
设事务T1和T2,对数据库中的数据X进行操作,可能有如下几种情形,请问哪一种情形不会发生冲突操作
A.T1正在读X时,T2也要读X
B.T1正在读X时,T2要写X
C.T1正在写X时,T2也要写X
D.T1正在写X时,T2要读X
答案
参考答案:A
解析:只有在两个事务都在进行读操作时才肯定不会发生冲突。否则就会发生丢失更新问题。
设事务T1和T2,对数据库中的数据X进行操作,可能有如下几种情形,请问哪一种情形不会发生冲突操作
A.T1正在读X时,T2也要读X
B.T1正在读X时,T2要写X
C.T1正在写X时,T2也要写X
D.T1正在写X时,T2要读X
参考答案:A
解析:只有在两个事务都在进行读操作时才肯定不会发生冲突。否则就会发生丢失更新问题。
将相匹配的语句连起来。 | |
( )1. Here you are. ( )2. I like skipping. ( )3. What's this? ( )4. Pass me the rice, please. ( )5. What do you do at seven o'clock? ( )6. What's your favourite song? ( )7. What are they? ( )8. Do you like fish? ( )9. Does Tingting like rice? ( )10. What's the time? | A. I watch TV B. OK. C. Thank you. D. I like skipping, too. E. It's a monkey. F. Yes, I do. G. It's half past five. H. It's the ABC song. I. They are lions. J. No, she doesn't. |