对于学生信息表STUDENT（SNO， SNAME，SEX，AGE，DEPT)（STUDENT由学号SNO、姓名SNAME、性别SEX、年龄AGE、所在系DEPT 5个属性组成，其中SNO为主码），求年龄20～23岁之间的学生姓名和年龄，正确的语句是（ ）。

A．SELECT SNAME，AGE FROM STUDENT WHERE AGE>20 AND AGE<23

B． SELECT*FROM STUDENT WHERE AGE BETWEEN 20 AND 23

C．SELECT SNAME，AGE FROM STUDENT WHERE AGE BETWEEN 20 AND 23

D．以上均不正确

[单选题]对于学生信息表：student(sno，sname，sex，age，dept)，能够得到年龄在20岁到22岁之间的学生的姓名和学号的语句是A．SELECT * FROM student WHERE age BETWEEN 20 AND 22B．SELECT sname，sno FROM student WHERE age BETWEEN 20 AND 22C．SELECT sname，sno FROM student WHERE age＞=20D．SELECT sname，sno FROM st

[单选题]对于学生信息表：student(sno，sname，sex，age，dept)，如果把学生“张明”的姓名改为“张岩”，则正确的语句是A．UPDATE SET sname='张明'WHERE sname='张岩'B．UPDATE student SET shame='张明'WHERE shame='张岩'C．UPDATE student SET sname='张岩'D．UPDATE student SET sname='张岩'WHERE sname='张明'

[单选题]对于学生信息表：student(sno，sname，sex，age，dept)，能够得到年龄在20岁于22岁之间的学生的姓名和学号的语句是A．SELECT * FROM student WHERE age BETWEEN 20 AND 22B．SELECT sname，sno FROM student WHERE age BETWEEN 20 AND 22C．SELECT sname，sno FROM student WHERE age＞=20D．SELECT sname，sno FROM st

[单选题]对于学生信息表：student(sno，sname，sex，age，dept)，如果把学生“小明”的姓名改为“小强”，则正确的语句是（ ）。A．)UPDATE SET sname=‘小明’WHERE sname=‘小强’B．)UPDATE student SET sname=‘小明’WHERE sname=‘小强’C．)UPDATE student SET sname=‘小强’D．)UPDATE student SET sname=‘小强’WHERE sname=‘小明’

[单选题]对于学生信息表：student(sno，sname，sex，age，dept)，要查询所有刘姓学生的信息，正确的语句是A．SELECT * FROM student WHERE sname LIKE'刘 * 'B．SELECT * FROM student WHERE sname LIKE'刘 $'C．SELECT * FROM student WHERE sname LIKE'刘%'D．SELECT * FROM student WHERE sname LIKE'刘&'

[单选题]对于学生信息表：student(sno，shame，sex，age，dept)，如果把学生“张明”的姓名改为“张岩”，则正确的语句是A．UPDATE SET sname＝'张明'WHERE sname='张岩'B．UPDATE student SET sname＝'张明'WHERE sname＝'张岩'C．UPDATE student SET sname＝'张岩'D．UPDATE student SET sname＝'张岩'WHERE sname＝'张明'

[单选题]对于学生信息表：student(sno, sname, sex, age, dept)，能够得到年龄在20岁于22岁之间的学生的姓名和学号的语句是A．SELECT * FROM student WHERE age BETWEEN 20 AND 22B．SELECT sname, sno FROM student WHERE age BETWEEN 20 AND 22C．SELECT sname,sno FROM student WHERE age＞＝20D．SELECT shame,sno FR

[单选题]对于学生信息表：student(sno，sname，sex，age，grade)，查询学习成绩为空的学生的学号和姓名，下面语句正确的是A．SELECT sno，sname FROM student WHERE grade=NULLB．SELECT sno，sname FROM student WHERE grade IS NULLC．SELECT sno，age FROM student WHERE grade IS NULLD．SELECT sno，age FROM student WHERE

[单选题]对于学生信息表：student(sno, sname, sex, age, dept)，如果把学生“张明”的姓名改为“张岩”，则正确的语句是A．UPDATE SET sname='张明'WHERE sname='张岩'B．UPDATE student SET sname='张明' WHERE sname='张岩'C．UPDATE student SET sname='张岩'D．UPDATE student SET sname='张岩' WHERE sname='张明'

[单选题]设有学生信息关系STUDENT(sno, sname, sex, age, dept)。“查找信息系(IS系)中年龄小于20岁的学生的姓名”，该操作正确的关系代数表达式是______。Ⅰ．πsname(σdept='IS'∧age＜20(STUDENT))Ⅱ．σdept='IS'∧age＜20(πsname(STUDENT))Ⅲ．σsname(πdept='IS'∧age＜20(STUDENT))A．仅ⅠB．仅ⅡC．Ⅰ和ⅡD．Ⅱ和Ⅲ