关于查询命令SELECT sname FROM student WHERE sdept IN(SELECT sdept FROM student WHERE sname = '刘晨'),说法正确的是（）。
A: 功能是查询和刘晨所在同一系的学生姓名
B: IN可以换成=
C: IN不一定可以换成=
D: 该查询可以用连接实现
A: 功能是查询和刘晨所在同一系的学生姓名
B: IN可以换成=
C: IN不一定可以换成=
D: 该查询可以用连接实现
举一反三
- S_T数据库关系图如下:[img=332x128]17e448fc85e997f.jpg[/img]查询与“刘晨”在同一个系学习的学生,要求显示学生学号(Sno)、姓名(Sname)及系别(Sdept)。下列SQL语句正确的是()。 A: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept = (SELECT Sdept FROM Student WHERE Sname = '刘晨'); B: SELECT S1.Sno, S1.Sname , S1.Sdept FROM Student S1 , Student S2 WHERE S1.Sdept = S2.Sdept AND S2.Sname = '刘晨'; C: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept IN (SELECT Sdept FROM Student WHERE Sname = '刘晨'); D: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept LIKE (SELECT Sdept FROM Student WHERE Sname = '刘晨');
- 在所有学生中查询比计算机系学生平均年龄大的学生姓名，可以使用的查询语句是： A: SELECT Sname FROM Student WHERE Sage > ( SELECT AVG(Sage) FROM Student ); WHERE Sdept = 'CS' B: SELECT Sname FROM Student WHERE Sage > AVG( SELECT Sage FROM Student WHERE Sdept = 'CS' ); C: SELECT Sname FROM Student WHERE Sage > ( SELECT AVG(Sage) FROM Student WHERE Sdept = 'CS' ); D: SELECT Sname FROM Student WHERE AVG(Sage) > ( SELECT Sage FROM Student WHERE Sdept = 'CS' );
- 在所有学生中查询比计算机系所有学生年龄都要大的学生姓名,正确的查询语句是___________________。 A: SELECT Sname FROM Student WHERE Sage > ( SELECT MAX(Sage) FROM Student WHERE Sdept = 'CS'); B: SELECT Sname FROM Student WHERE Sage > ALL ( SELECT Sage FROM Student WHERE Sdept = 'CS'); C: SELECT Sname FROM Student S1 WHERE EXISTS ( SELECT Sage FROM Student S2 WHERE Sdept = 'CS' AND S1.Sage > S2.Sage); D: SELECT Sname FROM Student S1 WHERE NOT EXISTS ( SELECT * FROM Student S2 WHERE Sdept = 'CS' AND S1.Sage <= S2.Sage);
- 在student（sno，sname，ssex，sage，sdept）表中，查询学生姓名中包含“大”或“小”的学生信息。以下查询语句正确的是（ ）。 A: select * from student where sname in( '_[大小]%') B: select * from student where sname ='%大%' or sname='%小%' C: select * from student where sname like'%大%' or sname like'%小%' D: select * from student where sname like '%[大小]%'
- 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&'