We are the Grade Nine students in ______ middle schools.
A.junior
B.senior
C.primary
D.elementary
A.junior
B.senior
C.primary
D.elementary
A.为student表的grade列创建了一个普通索引
B.为student表的grade列创建了一个唯一索引
C.为student表的grade列创建了一个空间索引
D.为student表的grade列创建了一个全文索引
A. UPDATE S
SET grade=85
WHERE SN=’王二’ AND CN=’化学’
B. UPDATE S
SET grade=’85’
WHERE SN=’王二’ AND CN=’化学’
C. UPDATE grade=85
WHERE SN=’王二’ AND CN=’化学’
D. UPDATE grade=’85’
WHERE SN=’王二’ AND CN=’化学’
有 这样三个表:学生表S、课程表C和学生选课表SC,它们的结构如下:S(S#,SN,SEX,AGE,DEPT)、C(C#,CN)、 SC(S#,C#,GRADE)。其中:S#为学号,SN为姓名,SEX为性别,AGE为年龄,DEPT为系别,C#为课程号,CN为课程名,GRADE 为成绩。要求如下:检索选修课程"C2"的学生中成绩最高的学生的学号。正确的SELECT语句是()。
A、SELECT S# FROM SC WHERE C#="C2" AND GRADE>=(SELECT GRADE FROM SC WHERE C#="C2")
B、SELECT S# FROM SC WHERE C#="C2" AND GRADE>(SELECT GRADE FROM SC WHERE C#="C2")
C、SELECT S# FROM SC WHERE C#="C2" AND GRADE NOT IN(SELECT GRADE FROM SC WHERE C#="C2")
D、SELECT S# FROM SC WHERE C#="C2" AND GRADE=(SELECT MAX(GRADE)FROM SC WHERE C#="C2")
所有学员的成绩加10分。下列SQL语句正确的是()。
A、update students set Grade=Grade+10 where SID=1
B、update * set Grade=Grade+10
C、update * from stedents set Grade=Grade+10
D、update students set Grade=Grade+10
设有关系STUDENT(S#,SNAME,SDEPT,MNAME,CNAME,GRADE),(S#,CNAME)为候选码,设关系中有如下函数依赖:
(S#,CNAME)→SNAME,SDEPT,MNAME
S#→SNAME,SDEPT,MNAME
(S#,CNAME)→GRADE
SDEPT→MNAME
关系STUDENT属于第几范式?并说明理由。
A. ADD
INTO S
VALUES(’张二’,’化学’,’80’)
B. INSERT
INTO S
VALUES(’张二’,’化学’,’80’)
C. ADD
INTO S
VALUES(’张二’,’化学’,80)
D. INSERT
INTO S
VALUES(’张二’,’化学’,80)
A. ADD
INTO S
VALUES(’张二’,’化学’,’80’)
B. INSERT
INTO S
VALUES(’张二’,’化学’,’80’)
C. ADD
INTO S
VALUES(’张二’,’化学’,80)
D. INSERT
INTO S
VALUES(’张二’,’化学’,80)