SQL-99标准规定的事务的四个隔离级别中，能解决幻影读现象的级别是______。
A．READ UNCOMMITTED
B．READ COMMITTED
C．REPEATABLE READ
D．SERIALIZABLE
参考答案：D
解析： 本题考查对并发事务处理隔离的掌握。
事务的四个隔离级别从READ UNCOMMITTED、READ COMMITTED、REPEATABLE READ到SERIALIZABLE，逐级加强，依次解决丢失修改、读脏数据、不可重复读、读幻影四个不一致问题，且后一级别同时解决了前一级别己解决的问题。
每空限填空一词，有些词需要做相应的变化。其中有两个多余的选项。
There were many stories in 2011 that showed our love in the beauty of mankind. Today I want to tell you a 小题1:____ story about Meng Peijie. She is still a student in a college now, but she was 小题2:___ as one of 10 recipients of its “Moving China” award by CCTV in 2011. Meng Peijie was born in Sha’anxi Province in 1991. After her 小题3:___ death in a car accident in 1996, her mother decided to send her to Liu Fangying. Liu Fangying’s family lived more 小题4: than before. But it only lasted three years of happiness, then Liu didn’t walk anymore and had to stay in bed. 小题5:, her husband left the home and never returned. Liu was so sad that she wanted to kill 小题6: by taking pills. But Meng Peijie found the pills, destroyed them and cried “Don’t die, mum. You’re the only one who 小题7: for me. You and I make a home.” It was only her 小题8: birthday at that time. Meng began cooking, doing housework and taking care of her mother. But Meng 小题9: so short that she had to stand on the chair to reach the cooker. She fell off it for many times. Meng said, “I’d rather go hungry as long as my mother can eat properly. I think my mother would do the same for me if I couldn’t walk.” Liu Fangying said, “I wish to thank her natural mother for 小题10: me such a good daughter.” What a kind-hearted girl she is! We should learn from her ----learn to be grateful: care for everyone and thank everyone. |