(8) SELECT (9)DISTINCT<Select_list>
(1) FROM <left_table> (3) <join_type>JOIN<right_table>
(2) ON<join_condition>
(4) WHERE<where_condition>
(5) GROUP BY<group_by_list>
(6) WITH {CUBE|ROLLUP}
(7) HAVING<having_condtion>
(10) ORDER BY<order_by_list>
(11) LIMIT<limit_number>

select t1.sid,sname
from
(select sid,max(score)
from SC group by sid having max(score)<60)as t1
left join student on t1.sid=student.sid

select a.sid,sname
from
(select sid,count(cid) from SC
group by sid
having count(cid)<(select count(cid) from course))as a
left join student on a.sid=student.sid;

select sid,sname
from Student
where sid in
(select distinct sid   #查询学生学号sid
from SC
where cid
in(select cid from SC where sid='01'))  #在成绩表中查出学号为01的学生课程
and sid!='01';

select sid,sname
from Student     #在student表中查出符合下面条件对应的学号和姓名
where sid
in
(SELECT
sid
from
(select *    #查出所有课中和01重合的课
from SC as a
where cid
in
(select cid from SC where sid='01'))b  #01学过的课
group by sid
having count(cid)=(select count(cid) FROM SC as c where sid='01')) #按学号分组后筛选出和01的学的课程数相等的学号
and sid!='01'   #查出学号姓名后排除掉01本身

暂跳过update题目

select sname
from Student
where sid
not in(select distinct sid   #not in 不在***里
from SC
left join course on
SC.cid=course.cid
left join teacher on
course.tid=teacher.tid
where tname='张三')

select t.sid,sname,avg_score  #对子查询引用
from
(
select sid,count(if(score<60,cid,null)),avg(score)as avg_score #这里的自查询要对平均数avg（score）重命名，因为下一步的查询要对其引用
from SC
group by sid
having count(if(score<60,cid,null))>=2
)t
left join student
on t.sid=student.sid

select *
from
(select student.sid,sname,sage,ssex,cid,score
FROM student left join SC on student.sid=SC.sid
where cid='01' and score<60)t
order by score desc

select sid,avg(score)as avg_score
from SC
group by sid
order by avg_score desc

select t.cid,any_value(cname)as 课程名称,max(score)as 最高分,
min(score)as 最低分,avg(score) as 平均分,
sum(及格)/count(sid) as 及格率,
sum(中等)/count(sid) as 中等率,
sum(优良)/count(sid) as 优良率,
sum(优秀)/count(sid) as 优秀率
from
(select *,case when score>=60 then 1 else 0 end as 及格,
case when score>=70 and score<80 then 1 else 0 end as 中等,
case when score>=80 and score<90 then 1 else 0 end as 优良,
case when score>=90 then 1 else 0 end as 优秀
from SC)t
left join course on t.cid=course.cid
group by cid
order by cid

select cid,avg(score) as avg_score,
count(if(score>=60,sid,null))/count(sid) as pass_rate
from SC
GROUP BY(cid) order by avg(score),pass_rate

select sid,sum(score)
from SC
group by (sid)
order by sum(score) desc

select course.tid,SC.cid,avg(score)as avg_score
from course left join SC on course.cid=SC.cid
group by tid,cid
order by avg(score) desc

select cid,sid,score
from
(select cid,sid,score,
row_number() over(partition by cid order by score desc)as ranking
from SC)c
where ranking>=2 and ranking<=3

#注意case when 前用sum求和，表示满足条件的人数的求和，而不是计次！！
select SC.cid,cname,
concat(round(100*sum(case when score between 85 and 100 then 1 else 0 end)/count(sid),2),'%') as '[100-85]',
concat(round(100*sum(case when score between 70 and 85 then 1 else 0 end)/count(sid),2),'%') as '[85-70]',
concat(round(100*sum(case when score between 60 and 70 then 1 else 0 end)/count(sid),2),'%') as '[70-60]',
concat(round(100*sum(case when score<=60 then 1 else 0 end)/count(sid),2),'%') as '[0-60]'
from SC left join course on SC.cid=course.cid
GROUP BY SC.cid,cname

select sid,avg_score,row_number() over(order by avg_score desc)as ranking
from (SELECT sid,avg(score)as avg_score from SC group by sid order by avg_score desc)a

select *
from
(select cid,score,row_number() over(partition by cid order by score desc)as rankk
from SC)a where rankk<=3

select cid,count(sid)as 人数
from SC
group by cid

select sid
from
(select sid,count(cid)as 选课数
from SC
group by sid)a
where 选课数=1

select ssex,count(distinct sid)as 人数
from student
group by ssex

select *
from Student
where sname like "%风"

select sname,ssex,count(sid)
from Student
group by ssex,sname
having count(sid)>=2

select * from student where year(sage)='1990'

select cid,avg(score)as avg_score
from SC
group by cid
order by avg_score,cid desc

selectsc.sid,sname,cname,score
from sc
left join courseon sc.cid=course.cid
left join teacheron course.tid=teacher.tid
left join studenton sc.sid=student.sid
where tname='张三'
order by score desc
limit 1;

select student.*,score
from student inner join SC on student.sid=SC.sid
inner join course on SC.cid=course.cid
inner join teacher on course.tid=teacher.tid
where tname='张三' and score=
(select max(score)
from teacher inner join course on teacher.tid=course.tid
inner join SC on course.cid=SC.cid
where tname='张三')

SELECT DISTINCT a.*
FROMsc AS a INNER JOIN sc AS b
WHERE a.score = b.score AND a.cid != b.cid ;

SELECT *
from
(select cid,sid,score,
rank() over(partition by cid order by score desc)as rankk
from SC)a
where rankk<=2

select cid,count(sid)
from SC
group by cid
having count(sid)>5

select sid,count(cid)
from SC
group by sid
having count(cid)>=2

select SC.sid,any_value(sname),any_value(sage),any_value(ssex)
from SC left join student
on SC.sid=student.sid
group by SC.sid
having count(cid)=
(select count(distinct cid)
from SC)

select sid,year(now())-year(sage) as 年龄  #年份相减，四舍五入
from student

select sid,sname
from student
where week(now())=week(sage)

select sid,sname
from student
where week(now())+1=week(sage)

select sid,sname
from student
where month(sage)=month(now())

select sid,sname
from student
where month(sage)=month(now())+1