【单选题】
Lucy,who did not even go to grade school, had no ________of a job at the time.
【单选题】
设关系数据库中一个表S的结构为:S(SN,CN,grade),其中SN为学生名,CN为课程名,二者均为字符型;grade为成绩,数值型,取值范围0-100。若要更正王二的化学成绩为85分,则可用( )。
①
UPDATE S
SET grade=85
WHERE SN=’王二’ AND CN=’化学’
②
UPDATE S
SET grade=’85’
WHERE SN=’王二’ AND CN=’化学’
③
UPDATE grade=85
WHERE SN=’王二’ AND CN=’化学’
④
UPDATE grade=’85’
WHERE SN=’王二’ AND CN=’化学’
【单选题】
After failing the exams three times, Jack realized that he’d never ____in English.
【判断题】
A: You know, I have three kids now. B: Thats terrific.
【单选题】
数据库中要求学生的成绩Grade必须是一个(0,100)的整数,则语义约束应属于( )。
【单选题】
设SC表中记录成绩的列为:Grade,类型为int。若在查询成绩时,希望将成绩按‘优’、‘良’、‘中’、‘及格’和‘不及格’形式显示,正确的Case函数是( )。
①
Case Grade
When 90~100THEN优
When 80~89THEN良
When 70~79THEN中
When 60~69THEN及格
Else不及格
End
②
Case
When Gradebetween 90 and 100THENGrade = 优
When Gradebetween 80 and 89THENGrade = 良
When Gradebetween 70 and 79THENGrade = 中
When Gradebetween 60 and 69THENGrade = 及格
ElseGrade = 不及格
End
③
Case
When Gradebetween 90 and 100THEN优
When Gradebetween 80 and 89THEN良
When Gradebetween 70 and 79THEN中
When Gradebetween 60 and 69THEN及格
Else不及格
End
④
Case Grade
When 90~100THEN Grade = 优
When 80~89THEN Grade = 良
When 70~79THEN Grade = 中
When 60~69THEN Grade = 及格
ElseGrade = 不及格
End
【单选题】
Three planes are waiting to _______.
【判断题】
There are three morphemes in the word “untouchable”.
【单选题】
They invited the three of ____, Bob, Joe, and ____.
【单选题】
对于学生--选课--课程的三个关系:S(S#,SNAME,SEX,AGE)SC(S#,C#,GRADE)C(C#,CNAME,TEACHER)为了提高查询速度,对SC表创建唯一索引,应建___个组上。