已知有关系“STUDENT”，则关系运算σANE＜80(STUDENT)用SQL语句表示为 (52) 。
A: SELECT( * )FROM STUDENT WHERE AVE ＜ 80
B: SELECT( * ) FROM STUDENT HAVING AVE ＜ 80
C: SELECT(AVE) FROM STUDENT WHERE AVE ＜ 80
D: SELECT(AVE） FROM STUDENT HAVING AVE ＜ 80
A: SELECT( * )FROM STUDENT WHERE AVE ＜ 80
B: SELECT( * ) FROM STUDENT HAVING AVE ＜ 80
C: SELECT(AVE) FROM STUDENT WHERE AVE ＜ 80
D: SELECT(AVE） FROM STUDENT HAVING AVE ＜ 80
举一反三
- 查询所有成绩均大于80分的学生姓名,应执行( )语句 A: SELECT SNAME FROM STUDENT WHERE EXISTS (SELECT *FROM SC WHERE STUDENSNO = SC.SNO AND GRADE> 80); B: SELECT SNAME FROM STUDENT WHERE EXISTS (SELECT *FROM SC WHERE STUDENSNO = SC.SNO AND GRADE C: SELECT SNAME FROM STUDENT WHERE NOT EXISTS (SELECT *FROM SC WHERE STUDENSNO = SC.SNO AND GRADE D: SELECT SNAME FROM STUDENT WHERE NOT EXISTS (SELECT *FROM SC WHERE STUDENSNO = SC.SNO AND GRADE> 80);
- 下列 SQL 语句select * from student where sno = '05880101'union select * from student where sno = '05880102'与此查询语句等价的选项是( )。 A: select * from student where sno= '05880101' and sno= '05880102' B: select * from student where sno= '05880101' or sno= '05880102' C: select * from student where sno= '05880101' D: select * from student where sno= '05880102'
- 若想查询student表中name为空值的记录，则正确的SQL语句是（ ）。 A: SELECT * FROM student WHERE name = NULL; B: SELECT * FROM student WHERE name like NULL; C: SELECT * FROM student WHERE name = 'NULL'; D: SELECT * FROM student WHERE name is NULL;
- 若想查询student表中name为空值的记录，则正确的SQL语句是（1.0分） A: select * from student where name = null; B: select * from student where name link null; C: select * from student where name = 'null'; D: select * from student where name is null;
- 查询所有非计算机系学生的信息，不正确的SQL语句是：（ ） A: SELECT * FROM Student WHERE Sdept != 'CS'; B: SELECT * FROM Student WHERE NOT Sdept = 'CS'; C: SELECT * FROM Student WHERE Sdept IN ('MA', 'IS'); D: SELECT * FROM Student WHERE NOT Sdept IN ('CS');