學生課程成績老師，四張表

學生表

成績表

課程表

老師表

查詢"01"課程比"02"課程成績高的學生的信息及課程分數

//連接表時對連接的表加條件
select s.s_name,s.s_id,s.s_birth,s.s_sex,sc1.s_score
from student s
left join score sc1
on s.s_id=sc1.s_id and sc1.c_id=01
left join score sc2
on s.s_id=sc2.s_id and sc2.c_id=02
where sc1.s_score>sc2.s_score;
//
select sc1.s_id,sc1.c_id,sc1.s_score
from
(
select *
from score where c_id=01
)sc1
left join 
(
select *
from score where c_id=02
)sc2
on sc1.s_id=sc2.s_id
where sc1.s_score>sc2.s_score

查詢"01"課程比"02"課程成績低的學生的信息及課程分數

select s.s_name,s.s_id,s.s_birth,s.s_sex,sc1.s_score
from student s
left join score sc1
on s.s_id=sc1.s_id and sc1.c_id=01
left join score sc2
on s.s_id=sc2.s_id and sc2.c_id=02
where sc1.s_score < sc2.s_score;

select sc1.s_id,sc1.c_id,sc1.s_score
from
(
select *
from score where c_id=01
)sc1
left join 
(
select *
from score where c_id=02
)sc2
on sc1.s_id=sc2.s_id
where sc1.s_score<sc2.s_score

查詢平均成績大於等於60分的同學的學生編號和學生姓名和平均成績

select s.s_id,s.s_name,avg(sc.s_score) avg_score
from student s
left join score sc
on s.s_id=sc.s_id
group by s.s_id,s.s_name
having avg(sc.s_score)>60;
-一步應該最高效了普通辦法

查詢平均成績小於60分的同學的學生編號和學生姓名和平均成績
– (包括有成績的和無成績的)

select s.s_id,s.s_name,avg(sc.s_score) avg_score
from student s
left join score sc
on s.s_id=sc.s_id
group by s.s_id,s.s_name
having avg(sc.s_score)<60;

查詢所有同學的學生編號、學生姓名、選課總數、所有課程的總成績

select s.s_id,s.s_name,count(*) countSelect,sum(sc.s_score) sumScore
from student s
left join score sc
on s.s_id=sc.s_id
group by s.s_id,s.s_name;

查詢"李"姓老師的數量

select count(*) from teacher where t_name like "李%";

查詢學過"張三"老師授課的同學的信息

//打出後三張大表，student直接join
select *
from student s
where s.s_id in(
SELECT sc.s_id
from score sc
LEFT JOIN course co 
ON sc.c_id=co.c_id 
LEFT JOIN teacher te 
ON co.t_id=te.t_id
where t_name='張三'
);


Launching Job 3 out of 3
Time taken: 3.627 seconds, Fetched: 6 row(s)

//
select *
from student s
where s.s_id in
(
select sc.s_id
from score sc
join
(
select c.c_id
from course c
where c.t_id in
(
select t.t_id
from teacher t
where t.t_name='張三'
)
)t2
on sc.c_id=t2.c_id
)


//
select *
from student s
where exists
(
select sc.s_id
from score sc
join
(
select c.c_id
from course c
where c.t_id in
(
select t.t_id
from teacher t
where t.t_name='張三'
)
)t2
on sc.c_id=t2.c_id
where s.s_id=sc.s_id
)

//
SELECT stu.* 
FROM student stu 
JOIN score sc 
ON stu.s_id=sc.s_id 
JOIN course co 
ON sc.c_id=co.c_id 
JOIN teacher te 
ON co.t_id=te.t_id 
WHERE t_name='張三'




//全連接法
SELECT stu.s_id,stu.s_name,stu.s_birth,stu.s_sex
FROM student stu 
LEFT JOIN score sc 
ON stu.s_id=sc.s_id 
LEFT JOIN course co 
ON sc.c_id=co.c_id 
LEFT JOIN teacher te 
ON co.t_id=te.t_id
where t_name='張三';

Launching Job 3 out of 3
Time taken: 3.693 seconds, Fetched: 6 row(s)

//
select s.s_id,s.s_name,s.s_birth,s.s_sex
from student s,
(
select
s.s_id
from score s
left join
(
select c.c_id
from course c,(select t_id tid from teacher where t_name='張三')t
where c.t_id=t.tid
)t2
on s.c_id=t2.c_id
where s.c_id=t2.c_id
)t3
where s.s_id=t3.s_id

Launching Job 3 out of 3
Time taken: 3.689 seconds, Fetched: 6 row(s)

查詢沒學過"張三"老師授課的同學的信息

select *
from student s
where s.s_id not in(
SELECT stu.s_id
FROM student stu 
LEFT JOIN score sc 
ON stu.s_id=sc.s_id 
LEFT JOIN course co 
ON sc.c_id=co.c_id 
LEFT JOIN teacher te 
ON co.t_id=te.t_id
where t_name='張三'
);

Launching Job 9 out of 9
Time taken: 10.695 seconds, Fetched: 2 row(s)

select *
from student s
where s.s_id not in(
SELECT sc.s_id
from score sc
LEFT JOIN course co 
ON sc.c_id=co.c_id 
LEFT JOIN teacher te 
ON co.t_id=te.t_id
where t_name='張三'
);

Launching Job 7 out of 7
Time taken: 8.351 seconds, Fetched: 2 row(s)

查詢學過編號爲"01"並且也學過編號爲"02"的課程的同學的信息

select *
from student s
left join score sc1
on s.s_id=sc1.s_id and sc1.c_id=01
left join score sc2
on s.s_id=sc2.s_id and sc2.c_id=02
where sc1.s_score is not null and sc2.s_score is not null;

查詢學過編號爲"01"但是沒有學過編號爲"02"的課程的同學的信息

select s.s_id,s.s_name,s.s_birth,s.s_sex
from student s
left join score sc1
on s.s_id=sc1.s_id and sc1.c_id=01
left join score sc2
on s.s_id=sc2.s_id and sc2.c_id=02
where sc1.s_score is not null and sc2.s_score is null;

查詢沒有學全所有課程的同學的信息

select sc.s_id
from score sc,(select count(*) cou from course) cou_course
group by sc.s_id,cou_course.cou
having count(sc.s_score)<cou_course.cou

查詢至少有一門課與學號爲"01"的同學所學相同的同學的信息

select s.*
from student s
left join score sc1
on s.s_id=sc1.s_id and sc1.c_id='01'
left join score sc2
on s.s_id=sc2.s_id and sc2.c_id='02'
left join score sc3
on s.s_id=sc3.s_id and sc3.c_id='03'
where sc1.c_id!=null or sc2.c_id!=null or sc3.c_id!=null and s.s_id!='01'
;

select distinct(s.s_name),s.s_sex,s.s_birth,s.s_id
from student s
join score sc
on s.s_id=sc.s_id
where s.s_id!='01' and sc.c_id in
(
select
c_id
from score 
where s_id='01'
)

查詢和"01"號的同學學習的課程完全相同的其他同學的信息

//將01同學的數課程轉化爲數組和其他所有同學按照課程轉化爲數組的表join
select t1.s_name,t1.s_id
from
(
select s.s_name,s.s_id,collect_list(sc.c_id) arr_cid
from student s
join score sc
on s.s_id=sc.s_id
group by s.s_name,s.s_id
)t1
join
(
select
collect_list(c_id) arr_cid
from score 
where s_id='01'
)t2
on t1.arr_cid=t2.arr_cid
where t1.s_id!='01'

查詢沒學過"張三"老師講授的任一門課程的學生姓名

select *
from student s
where s.s_id not in(
SELECT sc.s_id
from score sc
LEFT JOIN course co 
ON sc.c_id=co.c_id 
LEFT JOIN teacher te 
ON co.t_id=te.t_id
where t_name='張三'
);

查詢兩門及其以上不及格課程的同學的學號，姓名及其平均成績

//先得到不及格的所有同學然後分組統計
select t.s_name,t.s_id,round(avg(t.s_score),2)
from
(
select s.s_name,s.s_id,sc.s_score
from
student s
join score sc
on s.s_id=sc.s_id
where sc.s_score < 60
)t
group by t.s_id,t.s_name
having count(*)>=2

檢索"01"課程分數小於60，按分數降序排列的學生信息

SELECT *
FROM student s
LEFT JOIN score sc
ON s.s_id=sc.s_id
WHERE c_id='01'
AND s_score<60
ORDER BY  s_score

按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績

//直接窗口函數取最前面到最後面的平均值
select s_id,s_score,
round(avg(nvl(s_score,0)) over(partition by s_id order by s_score desc rows between unbounded preceding and unbounded following ),1) avg_sc
from score

查詢各科成績最高分、最低分和平均分：以如下形式顯示：課程ID，課程name，最高分，最低分，平均分，及格率，中等率，優良率，優秀率
–及格爲>=60，中等爲：70-80，優良爲：80-90，優秀爲：>=90

//按照成績列將滿足條件置爲1不滿足爲0，然後進行求和就得出了每一個條件下的總人數，然後除以總人數

select c.c_id,c.c_name,
round(sum(case when sc.s_score >= 90 then 1 else 0 end)/count(*),1) exce,
round(sum(case when sc.s_score>=80 and sc.s_score<90 then 1 else 0 end)/count(*),1) good,
round(sum(case when sc.s_score >=70 and sc.s_score <80 then 1 else 0 end)/count(*),1) mid,
round(sum(case when sc.s_score >= 60 and sc.s_score <70 then 1 else 0 end)/count(*),1) seve,
max(sc.s_score) max_sc,
min(sc.s_score) min_sc,
round(avg(sc.s_score),1) avg_sc
from course c
left join score sc
on c.c_id=sc.c_id
group by c.c_id,c.c_name;


//

{"good":"0.33","notseve":"0.33","mid":"0.33"}
{"good":"0.5","seve":"0.17","notseve":"0.17","exce":"0.17"} 
{"good":"0.33","notseve":"0.33","exce":"0.33"}

//
一個新列是成績的分類，然後是max等其他，將分類和人數除以總人數合併（cancat），然後將每一科的所有拼接的字符串轉爲list然後拼爲總字符串然後轉爲map，

select t2.c_id,
t2.c_name,
t2.max_sc,
t2.min_sc,
t2.avg_sc,
nvl(t2.type['exce'],0) exec,
nvl(t2.type['good'],0) good,
nvl(t2.type['mid'],0) mid,
nvl(t2.type['seve'],0) seve
from
(
select t1.c_id,
t1.c_name,
str_to_map(concat_ws(',',collect_list(t1.type)),',','_') type,
t1.max_sc,
t1.min_sc,
t1.avg_sc
from
(
select t.c_id,
t.c_name,
concat(t.type,'_',round(count(*)/t.cou_,2)) type,
t.max_sc,
t.min_sc,
t.avg_sc
from
(
select c.c_id,c.c_name,
case when sc.s_score >= 90 then 'exce' 
when sc.s_score>=80 and sc.s_score<90 then 'good'
when sc.s_score >=70 and sc.s_score <80 then 'mid'
when sc.s_score >= 60 and sc.s_score <70 then 'seve'
else 'notseve' end type,
count(c.c_name) over(partition by c.c_name) cou_,
max(sc.s_score) over(partition by c.c_id) max_sc,
min(sc.s_score) over(partition by c.c_id) min_sc,
round(avg(sc.s_score) over(partition by c.c_id),1) avg_sc
from course c
left join score sc
on c.c_id=sc.c_id
)t
group by t.c_id,t.c_name,t.type,t.cou_,t.max_sc,t.min_sc,t.avg_sc
)t1
group by t1.c_id,t1.c_name,t1.max_sc,t1.min_sc,t1.avg_sc
)t2
group by t2.c_id,t2.c_name,t2.max_sc,t2.min_sc,t2.avg_sc,t2.type

按各科成績進行排序，並顯示排名(實現不完全)

select s.*,rank() over(partition by s.c_id order by s.s_score) rank
from score s

查詢學生的總成績並進行排名

select s_name,sum(nvl(s_score,0)) su_sc
from student s 
left join score sc
on s.s_id=sc.s_id
group by s_name
order by su_sc desc

查詢不同老師所教不同課程平均分從高到低顯示

select c.t_id,c.c_name,round(avg(nvl(sc.s_score,0)),2) avg_score
from course c
left join score sc
on c.c_id=sc.c_id
group by c.t_id,c.c_name
order by avg_score desc

查詢所有課程的成績第2名到第3名的學生信息及該課程成績

select
t1.*
from
(
select s.*,sc.c_id,sc.s_score,
row_number() over(partition by sc.c_id order by sc.s_score desc) rank
from score sc
left join student s
on sc.s_id=s.s_id
)t1
where t1.rank>1 and rank <=3

統計各科成績各分數段人數：課程編號,課程名稱,[100-85],[85-70],[70-60],[0-60]及所佔百分比

select c.c_id,c.c_name,
round(sum(case when sc.s_score>85 and sc.s_score <=100 then 1 else 0 end)/count(*),1) `[100-85]`,
round(sum(case when sc.s_score>85 and sc.s_score <=85 then 1 else 0 end)/count(*),1) `[85-70]`,
round(sum(case when sc.s_score>60 and sc.s_score <=70 then 1 else 0 end)/count(*),1) `[70-60]`,
round(sum(case when sc.s_score>0 and sc.s_score <=60 then 1 else 0 end)/count(*),1) `[0-60]`
from score sc
join course c
on sc.c_id=c.c_id
group by c.c_id,c.c_name

查詢學生平均成績及其名次

select sc.s_id,
avg(if null(sc.s_score,0)) avg_sc ,
row_number() over(sort by sc.avg)
from score sc
group by sc.s_id

查詢各科成績前三名的記錄

select t.*
from
(
select sc.*,
row_number() over(partition by sc.c_id order by sc.s_score desc) rank
from score sc
)t
where t.rank <=3;

查詢每門課程被選修的學生數

select c_id,count(*) cou_per
from score
group by c_id

查詢出只有兩門課程的全部學生的學號和姓名

select s_name,s.s_id
from score sc
left join student s
on sc.s_id=s.s_id
group by s.s_id,s_name
having count(*)=2;

查詢男生、女生人數

SELECT s_sex,COUNT(*) cou_per
FROM student
GROUP BY s_sex;

查詢名字中含有"風"字的學生信息

select *
from student
where s_name like '%風%'

查詢同名同性學生名單，並統計同名人數

select s.s_name,s.s_sex,count(*) cou_per
from student s
group by s.s_name,s.s_sex

查詢1990年出生的學生名單

//
SELECT s_name 
FROM student
WHERE s_birth LIKE '1990%'

//
select s_name
from student
where year(s_birth)='1990'

查詢每門課程的平均成績，結果按平均成績降序排列，平均成績相同時，按課程編號升序排列
```
select avg(s_score)
from score
group by c_id
order by avg(s_score) desc, (c_id) avg
```

查詢平均成績大於等於85的所有學生的學號、姓名和平均成績

select s.s_id,s.s_name,avg(sc.s_score) avg_sc
from student s
left join score sc
on s.s_id = sc.s_id
group by sc.s_score
having avg_sc>=85

查詢課程名稱爲"數學"，且分數低於60的學生姓名和分數

SELECT s_name,s_score
FROM student stu LEFT JOIN score sc ON stu.s_id=sc.s_id
LEFT JOIN course co ON sc.c_id=co.c_id
WHERE s_score < 60 AND c_name ='數學'

查詢所有學生的課程及分數情況；

SELECT s_name,c_name,s_score
FROM student stu 
LEFT JOIN score sc 
ON stu.s_id=sc.s_id

查詢任何一門課程成績在70分以上的姓名、課程名稱和分數；

select s.s_name,c.c_name,sc.s_score
FROM student s
LEFT JOIN score sc 
ON s.s_id=sc.s_id
LEFT JOIN course c 
ON sc.c_id=c.c_id
where sc.s_score>70

查詢不及格的課程

//
SELECT s.s_name,sc.c_name,sc.s_score
FROM student s
LEFT JOIN score sc 
ON s.s_id=sc.s_id
WHERE sc.s_score<60

//
select c_id,avg(score)
from score 
group by c_id
having avg(score)<=60

查詢課程編號爲01且課程成績在80分以上的學生的學號和姓名；

SELECT stu.s_id,s_name
FROM student stu 
LEFT JOIN score sc 
ON stu.s_id=sc.s_id
LEFT JOIN course co 
ON sc.c_id=co.c_id
WHERE co.c_id=01
AND s_score>80

求每門課程的學生人數

select c_id,count(*) cou_per
score
group by c_id

查詢選修"張三"老師所授課程的學生中，成績最高的學生信息及其成績

select s.*,sc.s_score
FROM student s 
LEFT JOIN score sc 
ON s.s_id=sc.s_id 
LEFT JOIN course c 
ON sc.c_id=c.c_id 
LEFT JOIN teacher te 
ON c.t_id=te.t_id
where te.t_name='張三'
order by sc.s_score
limit 1;

查詢不同課程成績相同的學生的學生編號、課程編號、學生成績

select distinct(sc1.s_id),sc1.c_id,sc1.s_score
from score sc1,score sc2
where sc1.c_id!=sc2.c_id 
and sc1.s_score=sc2.s_score

查詢每門功成績最好的前兩名

select
t.s_id,t.c_id,
t.rank
from
(
select
s_id,c_id,
row_number() over(partition by c_id order by s_score desc) rank
from score
)t
where t.rank <= 2

統計每門課程的學生選修人數（超過5人的課程才統計）。要求輸出課程號和選修人數，查詢結果按人數降序排列，若人數相同，按課程號升序排列
```
SELECT c_id,COUNT(*)
FROM score
GROUP BY c_id
HAVING COUNT(*)>5
ORDER BY COUNT(*) DESC,c_id ASC
```

檢索至少選修兩門課程的學生學號

select sc.s_id
from score sc
group by s.s_id
having count(*)>=2

查詢選修了全部課程的學生信息

select
from score sc,count(select count(*) cou_per from course c) cou_per
where 
group by sc.s_id
having count(*) > cou_per

查詢各學生的年齡

methon1：
自定義UDF函數上傳使用
public class AgeCalculate extends UDF {
    public int evaluate(String str) {
        int age = 0;
        if (str.matches("\\d{4}(\\-|\\/|.)\\d{1,2}\\1\\d{1,2}")) {
            String[] dateStr = str.split("-");
            int year = Integer.parseInt(dateStr[0]);
            int month = Integer.parseInt(dateStr[1]);
            int day = Integer.parseInt(dateStr[2]);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            String nowDate = simpleDateFormat.format(new Date());
            String[] now = nowDate.split("-");
            int nowYear = Integer.parseInt(now[0]);
            int nowmonth = Integer.parseInt(now[1]);
            int nowDay = Integer.parseInt(now[2]);
            if (nowmonth==month && nowDay <= day ){
                age=nowYear-year-1;
            }else if (nowmonth< month){
                age=nowYear-year-1;
            }else {
                age=nowYear-year;
            }
        } else {
            System.out.println("you input don't matche str");
        }
        return age;
    }

    public static void main(String[] args) {
        new AgeCalculate().evaluate("2010-9-2");
    }

}

//
methon2：
select s_name,from_unixtime(curdate,'yyyy')-year(s_birth) 'age'
from student

查詢本週過生日的學生

select *
from student
where weekofyear(s_birth)=weekofyear(current_date());

查詢下週過生日的學生

select *
from student
where weekofyear(s_birth)=weekofyear(current_date())+1;

查詢本月過生日的學生

select * from student where month(s_birth)=month(current_date);

查詢下月過生日的學生

select * from student where month(s_birth)=month(current_date)+1;

Hive全實現經典五十題（持續優化）

學生課程成績老師，四張表

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