问题 单项选择题

数据库系统发生故障时,可以基于日志进行恢复。下面列出的条目中,为日志记录的内容的是 Ⅰ.事务开始信息 Ⅱ.更新信息 Ⅲ.提交信息 Ⅳ.事务中止信息

A.Ⅰ和Ⅱ

B.Ⅰ、Ⅱ和Ⅲ

C.Ⅱ、Ⅲ和Ⅳ

D.全部

答案

参考答案:D

解析: 日志记录主要有以下几种,用于记录数据库的写操作和事务处理过程中的重要事件: ①事务开始日志记录:<Tistart>,表示事务Ti开始: ②更新日志记录:<Ti,Xj,V1,V2>,表示事务Ti对数据项Xj执行修改操作。Xj的改前值是V1,改后值V2; ③事务提交日志记录:<Ticommit>,表示事务Ti提交; ④事务中止日志记录:<Tiabort>,事务Ti中止。

单项选择题
单项选择题

Many foreigners who have not visited Britain call all the inhabitants English, for they are used to thinking of the British Isles as England. (1) , the British Isles contain a variety of peoples, and only the people of England call themselves English. The others (2) to themselves as Welsh, Scottish, or Irish, (3) the case may be; they are often slightly annoyed (4) being classified as "English".

Even in England there are many (5) in regional character and speech. The chief (6) is between southern England and northern England. South of a (7) going from Bristol to London, people speak the type of English usually learnt by foreign students, (8) there are local variations.

Further north regional speech is usually " (9) " than that of southern Britain. Northerners are (10) to claim that they work harder than Southerners, and are more (11) They are open-hearted and hospitable; foreigners often find that they make friends with them (12) Northerners generally have hearty (13) : the visitor to Lancashire or Yorkshire, for instance, may look forward to receiving generous (14) at meal times.

In accent and character the people of the Midlands (15) a gradual change from the southern to the northern type of Englishman.

In Scotland the sound (16) by the letter "R" is generally a p sound, and "R" is often pronounced in words in which it would be (17) in southern English. The Scots are said to be a serious, cautious, thrifty people, (18) inventive and somewhat mystical. All the Celtic peoples of Britain (the Welsh, the Irish, the Scots) are frequently (19) as being more "fiery" than the English. They are (20) a race that is quite distinct from the English. (289 words)

Notes: fiery 暴躁的,易怒的。

(3)()

A.as

B.which

C.for

D.so