查询复习-英译汉

请练习以下语句,用文字说明其执行的功能

--

select 人数=count(studentid)

from students

--

select 人数=count(studentid),sclass

from students

group by sclass

--

select 人数=count(studentid),ssex

from students

group by ssex

--

select 人数=count(*),sclass,ssex

from students

group by ssex,sclass

--查询成绩表中各个科目的最高分(要显示科目ID)   (写语句)

--

select A.sname,B.score,C.Cname,A.sclass

from score as B, students as A,course as C

where A.studentID=B.studentID and B.courseID=C.courseID

--

select A.sname,B.score,B.courseID

from students as A

left outer join score as b

on A.studentID=B.studentID

--

select A.sname,B.score,B.courseID

from students as A

right outer join score as b

on A.studentID=B.studentID

--

use bbs

select s.sname,c.score,c.courseid

from score as c

inner join students as s

on s.studentID=c.studentID

where s.sname='刘邦'

--

select s.sname,c.courseid,c.score

from students as s,score as c

where s.studentid=c.studentid 

--

select c.studentid,a.cName,c.score 

from score as c 

inner join course as a

on c.courseid=a.courseid

where studentid like '2010012[0-1]'