--查询Student表中的所有记录的Sname、Ssex和Class列。
SELECT sname,ssex,class from Student
--查询教师所有的单位即不重复的Depart列。
SELECT DISTINCT depart from Teachear
--查询Student表的所有记录。
SELECT * from Student
--查询Score表中成绩在60到80之间的所有记录。
SELECT * from Score where Degree BETWEEN 60 and 80
-查询Score表中成绩为85，86或88的记录。
SELECT * from Score WHERE Degree IN('85','86','88')
--查询Student表中“95031”班或性别为“女”的同学记录。
SELECT * FROM Student WHERE Ssex='女'AND Class='95031''
--以Class降序查询Student表的所有记录。
SELECT * FROM Student ORDER BY class DESC
--以Cno升序、Degree降序查询Score表的所有记录。
SELECT *from Score ORDER BY degree DESC,cno asc
--查询“95031”班的学生人数。
SELECT count(*) from Student WHERE Class='95031'
-查询Score表中的最高分的学生学号和课程号
--SELECT a.Sno,b.Sname,a.Cno,a.Degree FROM Score a,Student b,Course c WHERE a.Sno = b.Sno and a.Cno=c.Cno and a.Cno='3-245'
select * from score order by degree desc --答案
--查询每门课的平均成绩。
SELECT cno,avg(degree) from Score GROUP BY Cno
--查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
SELECT avg(degree) FROM Score WHERE cno in (SELECT cno from Score GROUP BY cno having count(*)>5) and cno LIKE '3%' GROUP BY Cno
--查询分数大于70，小于90的Sno列。
--SELECT * FROM Score WHERE Degree BETWEEN 70 and 90
SELECT sno from Score WHERE Degree BETWEEN 70 and 90 --答案
