表結(jié)構(gòu)

–1.學(xué)生表 Student(s_id,s_name,s_birth,s_sex) –學(xué)生編號,學(xué)生姓名, 出生年月,學(xué)生性別 –2.課程表 Course(c_id,c_name,t_id) – –課程編號, 課程名稱, 教師編號 –3.教師表 Teacher(t_id,t_name) –教師編號,教師姓名 –4.成績表 Score(s_id,c_id,s_score) –學(xué)生編號,課程編號,分?jǐn)?shù)

2、測試數(shù)據(jù)

--建表 --學(xué)生表 CREATE TABLE `Student`(`s_id` VARCHAR(20),`s_name` VARCHAR(20) NOT NULL DEFAULT '',`s_birth` VARCHAR(20) NOT NULL DEFAULT '',`s_sex` VARCHAR(10) NOT NULL DEFAULT '',PRIMARY KEY(`s_id`) ); --課程表 CREATE TABLE `Course`(`c_id` VARCHAR(20),`c_name` VARCHAR(20) NOT NULL DEFAULT '',`t_id` VARCHAR(20) NOT NULL,PRIMARY KEY(`c_id`) ); --教師表 CREATE TABLE `Teacher`(`t_id` VARCHAR(20),`t_name` VARCHAR(20) NOT NULL DEFAULT '',PRIMARY KEY(`t_id`) ); --成績表 CREATE TABLE `Score`(`s_id` VARCHAR(20),`c_id` VARCHAR(20),`s_score` INT(3),PRIMARY KEY(`s_id`,`c_id`) ); --插入學(xué)生表測試數(shù)據(jù) insert into Student values('01' , '趙雷' , '1990-01-01' , '男'); insert into Student values('02' , '錢電' , '1990-12-21' , '男'); insert into Student values('03' , '孫風(fēng)' , '1990-05-20' , '男'); insert into Student values('04' , '李云' , '1990-08-06' , '男'); insert into Student values('05' , '周梅' , '1991-12-01' , '女'); insert into Student values('06' , '吳蘭' , '1992-03-01' , '女'); insert into Student values('07' , '鄭竹' , '1989-07-01' , '女'); insert into Student values('08' , '王菊' , '1990-01-20' , '女'); --課程表測試數(shù)據(jù) insert into Course values('01' , '語文' , '02'); insert into Course values('02' , '數(shù)學(xué)' , '01'); insert into Course values('03' , '英語' , '03'); --教師表測試數(shù)據(jù) insert into Teacher values('01' , '張三'); insert into Teacher values('02' , '李四'); insert into Teacher values('03' , '王五'); --成績表測試數(shù)據(jù) insert into Score values('01' , '01' , 80); insert into Score values('01' , '02' , 90); insert into Score values('01' , '03' , 99); insert into Score values('02' , '01' , 70); insert into Score values('02' , '02' , 60); insert into Score values('02' , '03' , 80); insert into Score values('03' , '01' , 80); insert into Score values('03' , '02' , 80); insert into Score values('03' , '03' , 80); insert into Score values('04' , '01' , 50); insert into Score values('04' , '02' , 30); insert into Score values('04' , '03' , 20); insert into Score values('05' , '01' , 76); insert into Score values('05' , '02' , 87); insert into Score values('06' , '01' , 31); insert into Score values('06' , '03' , 34); insert into Score values('07' , '02' , 89); insert into Score values('07' , '03' , 98);

3、測試題

-- 1、查詢"01"課程比"02"課程成績高的學(xué)生的信息及課程分?jǐn)?shù) select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a join score b on a.s_id=b.s_id and b.c_id='01'left join score c on a.s_id=c.s_id and c.c_id='02' or c.c_id = NULL where b.s_score>c.s_score -- 2、查詢"01"課程比"02"課程成績低的學(xué)生的信息及課程分?jǐn)?shù) select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a left join score b on a.s_id=b.s_id and b.c_id='01' or b.c_id=NULL join score c on a.s_id=c.s_id and c.c_id='02' where b.s_score<c.s_score -- 3、查詢平均成績大于等于60分的同學(xué)的學(xué)生編號和學(xué)生姓名和平均成績 select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from student b join score a on b.s_id = a.s_idGROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)>=60; -- 4、查詢平均成績小于60分的同學(xué)的學(xué)生編號和學(xué)生姓名和平均成績-- (包括有成績的和無成績的) select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from student b left join score a on b.s_id = a.s_idGROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)<60union select a.s_id,a.s_name,0 as avg_score from student a where a.s_id not in (select distinct s_id from score); -- 5、查詢所有同學(xué)的學(xué)生編號、學(xué)生姓名、選課總數(shù)、所有課程的總成績 select a.s_id,a.s_name,count(b.c_id) as sum_course,sum(b.s_score) as sum_score from student a left join score b on a.s_id=b.s_idGROUP BY a.s_id,a.s_name; -- 6、查詢"李"姓老師的數(shù)量 select count(t_id) from teacher where t_name like '李%'; -- 7、查詢學(xué)過"張三"老師授課的同學(xué)的信息 select a.* from student a join score b on a.s_id=b.s_id where b.c_id in(select c_id from course where t_id =(select t_id from teacher where t_name = '張三')); -- 8、查詢沒學(xué)過"張三"老師授課的同學(xué)的信息 select * from student c where c.s_id not in(select a.s_id from student a join score b on a.s_id=b.s_id where b.c_id in(select c_id from course where t_id =(select t_id from teacher where t_name = '張三'))); -- 9、查詢學(xué)過編號為"01"并且也學(xué)過編號為"02"的課程的同學(xué)的信息 select a.* from student a,score b,score c where a.s_id = b.s_id and a.s_id = c.s_id and b.c_id='01' and c.c_id='02'; -- 10、查詢學(xué)過編號為"01"但是沒有學(xué)過編號為"02"的課程的同學(xué)的信息 select a.* from student a where a.s_id in (select s_id from score where c_id='01' ) and a.s_id not in(select s_id from score where c_id='02') -- 11、查詢沒有學(xué)全所有課程的同學(xué)的信息 select s.* from student s where s.s_id in(select s_id from score where s_id not in(select a.s_id from score a join score b on a.s_id = b.s_id and b.c_id='02'join score c on a.s_id = c.s_id and c.c_id='03'where a.c_id='01')) -- 12、查詢至少有一門課與學(xué)號為"01"的同學(xué)所學(xué)相同的同學(xué)的信息 select * from student where s_id in(select distinct a.s_id from score a where a.c_id in(select a.c_id from score a where a.s_id='01')); -- 13、查詢和"01"號的同學(xué)學(xué)習(xí)的課程完全相同的其他同學(xué)的信息 select a.* from student a where a.s_id in(select distinct s_id from score where s_id!='01' and c_id in(select c_id from score where s_id='01')group by s_id having count(1)=(select count(1) from score where s_id='01')); -- 14、查詢沒學(xué)過"張三"老師講授的任一門課程的學(xué)生姓名 select a.s_name from student a where a.s_id not in (select s_id from score where c_id = (select c_id from course where t_id =(select t_id from teacher where t_name = '張三')) group by s_id); -- 15、查詢兩門及其以上不及格課程的同學(xué)的學(xué)號，姓名及其平均成績 select a.s_id,a.s_name,ROUND(AVG(b.s_score)) from student a left join score b on a.s_id = b.s_idwhere a.s_id in(select s_id from score where s_score<60 GROUP BY s_id having count(1)>=2)GROUP BY a.s_id,a.s_name -- 16、檢索"01"課程分?jǐn)?shù)小于60，按分?jǐn)?shù)降序排列的學(xué)生信息 select a.*,b.c_id,b.s_score from student a,score b where a.s_id = b.s_id and b.c_id='01' and b.s_score<60 ORDER BY b.s_score DESC; -- 17、按平均成績從高到低顯示所有學(xué)生的所有課程的成績以及平均成績 select a.s_id,(select s_score from score where s_id=a.s_id and c_id='01') as 語文,(select s_score from score where s_id=a.s_id and c_id='02') as 數(shù)學(xué),(select s_score from score where s_id=a.s_id and c_id='03') as 英語,round(avg(s_score),2) as 平均分 from score a GROUP BY a.s_id ORDER BY 平均分 DESC; -- 18.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(yōu)良率，優(yōu)秀率 --及格為>=60，中等為：70-80，優(yōu)良為：80-90，優(yōu)秀為：>=90 select a.c_id,b.c_name,MAX(s_score),MIN(s_score),ROUND(AVG(s_score),2),ROUND(100*(SUM(case when a.s_score>=60 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 及格率,ROUND(100*(SUM(case when a.s_score>=70 and a.s_score<=80 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 中等率,ROUND(100*(SUM(case when a.s_score>=80 and a.s_score<=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 優(yōu)良率,ROUND(100*(SUM(case when a.s_score>=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 優(yōu)秀率from score a left join course b on a.c_id = b.c_id GROUP BY a.c_id,b.c_name -- 19、按各科成績進(jìn)行排序，并顯示排名(實(shí)現(xiàn)不完全) -- mysql沒有rank函數(shù)select a.s_id,a.c_id,@i:=@i +1 as i保留排名,@k:=(case when @score=a.s_score then @k else @i end) as rank不保留排名,@score:=a.s_score as scorefrom (select s_id,c_id,s_score from score WHERE c_id='01' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC )a,(select @k:=0,@i:=0,@score:=0)sunionselect a.s_id,a.c_id,@i:=@i +1 as i,@k:=(case when @score=a.s_score then @k else @i end) as rank,@score:=a.s_score as scorefrom (select s_id,c_id,s_score from score WHERE c_id='02' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC )a,(select @k:=0,@i:=0,@score:=0)sunionselect a.s_id,a.c_id,@i:=@i +1 as i,@k:=(case when @score=a.s_score then @k else @i end) as rank,@score:=a.s_score as scorefrom (select s_id,c_id,s_score from score WHERE c_id='03' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC )a,(select @k:=0,@i:=0,@score:=0)s -- 20、查詢學(xué)生的總成績并進(jìn)行排名 select a.s_id,@i:=@i+1 as i,@k:=(case when @score=a.sum_score then @k else @i end) as rank,@score:=a.sum_score as score from (select s_id,SUM(s_score) as sum_score from score GROUP BY s_id ORDER BY sum_score DESC)a,(select @k:=0,@i:=0,@score:=0)s -- 21、查詢不同老師所教不同課程平均分從高到低顯示 select a.t_id,c.t_name,a.c_id,ROUND(avg(s_score),2) as avg_score from course aleft join score b on a.c_id=b.c_id left join teacher c on a.t_id=c.t_idGROUP BY a.c_id,a.t_id,c.t_name ORDER BY avg_score DESC; -- 22、查詢所有課程的成績第2名到第3名的學(xué)生信息及該課程成績 select d.*,c.排名,c.s_score,c.c_id from (select a.s_id,a.s_score,a.c_id,@i:=@i+1 as 排名 from score a,(select @i:=0)s where a.c_id='01' )cleft join student d on c.s_id=d.s_idwhere 排名 BETWEEN 2 AND 3UNIONselect d.*,c.排名,c.s_score,c.c_id from (select a.s_id,a.s_score,a.c_id,@j:=@j+1 as 排名 from score a,(select @j:=0)s where a.c_id='02' )cleft join student d on c.s_id=d.s_idwhere 排名 BETWEEN 2 AND 3UNIONselect d.*,c.排名,c.s_score,c.c_id from (select a.s_id,a.s_score,a.c_id,@k:=@k+1 as 排名 from score a,(select @k:=0)s where a.c_id='03' )cleft join student d on c.s_id=d.s_idwhere 排名 BETWEEN 2 AND 3; -- 23、統(tǒng)計(jì)各科成績各分?jǐn)?shù)段人數(shù)：課程編號,課程名稱,[100-85],[85-70],[70-60],[0-60]及所占百分比select distinct f.c_name,a.c_id,b.`85-100`,b.百分比,c.`70-85`,c.百分比,d.`60-70`,d.百分比,e.`0-60`,e.百分比 from score aleft join (select c_id,SUM(case when s_score >85 and s_score <=100 then 1 else 0 end) as `85-100`,ROUND(100*(SUM(case when s_score >85 and s_score <=100 then 1 else 0 end)/count(*)),2) as 百分比from score GROUP BY c_id)b on a.c_id=b.c_idleft join (select c_id,SUM(case when s_score >70 and s_score <=85 then 1 else 0 end) as `70-85`,ROUND(100*(SUM(case when s_score >70 and s_score <=85 then 1 else 0 end)/count(*)),2) as 百分比from score GROUP BY c_id)c on a.c_id=c.c_idleft join (select c_id,SUM(case when s_score >60 and s_score <=70 then 1 else 0 end) as `60-70`,ROUND(100*(SUM(case when s_score >60 and s_score <=70 then 1 else 0 end)/count(*)),2) as 百分比from score GROUP BY c_id)d on a.c_id=d.c_idleft join (select c_id,SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end) as `0-60`,ROUND(100*(SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end)/count(*)),2) as 百分比from score GROUP BY c_id)e on a.c_id=e.c_idleft join course f on a.c_id = f.c_id -- 24、查詢學(xué)生平均成績及其名次 select a.s_id,@i:=@i+1 as '不保留空缺排名',@k:=(case when @avg_score=a.avg_s then @k else @i end) as '保留空缺排名',@avg_score:=avg_s as '平均分'from (select s_id,ROUND(AVG(s_score),2) as avg_s from score GROUP BY s_id)a,(select @avg_score:=0,@i:=0,@k:=0)b; -- 25、查詢各科成績前三名的記錄-- 1.選出b表比a表成績大的所有組-- 2.選出比當(dāng)前id成績大的 小于三個(gè)的select a.s_id,a.c_id,a.s_score from score a left join score b on a.c_id = b.c_id and a.s_score<b.s_scoregroup by a.s_id,a.c_id,a.s_score HAVING COUNT(b.s_id)<3ORDER BY a.c_id,a.s_score DESC -- 26、查詢每門課程被選修的學(xué)生數(shù) select c_id,count(s_id) from score a GROUP BY c_id -- 27、查詢出只有兩門課程的全部學(xué)生的學(xué)號和姓名 select s_id,s_name from student where s_id in(select s_id from score GROUP BY s_id HAVING COUNT(c_id)=2); -- 28、查詢男生、女生人數(shù) select s_sex,COUNT(s_sex) as 人數(shù) from student GROUP BY s_sex -- 29、查詢名字中含有"風(fēng)"字的學(xué)生信息select * from student where s_name like '%風(fēng)%'; -- 30、查詢同名同性學(xué)生名單，并統(tǒng)計(jì)同名人數(shù) select a.s_name,a.s_sex,count(*) from student a JOIN student b on a.s_id !=b.s_id and a.s_name = b.s_name and a.s_sex = b.s_sexGROUP BY a.s_name,a.s_sex -- 31、查詢1990年出生的學(xué)生名單 select s_name from student where s_birth like '1990%' -- 32、查詢每門課程的平均成績，結(jié)果按平均成績降序排列，平均成績相同時(shí)，按課程編號升序排列 select c_id,ROUND(AVG(s_score),2) as avg_score from score GROUP BY c_id ORDER BY avg_score DESC,c_id ASC -- 33、查詢平均成績大于等于85的所有學(xué)生的學(xué)號、姓名和平均成績 select a.s_id,b.s_name,ROUND(avg(a.s_score),2) as avg_score from score aleft join student b on a.s_id=b.s_id GROUP BY s_id HAVING avg_score>=85 -- 34、查詢課程名稱為"數(shù)學(xué)"，且分?jǐn)?shù)低于60的學(xué)生姓名和分?jǐn)?shù) select a.s_name,b.s_score from score b LEFT JOIN student a on a.s_id=b.s_id where b.c_id=(select c_id from course where c_name ='數(shù)學(xué)') and b.s_score<60 -- 35、查詢所有學(xué)生的課程及分?jǐn)?shù)情況； select a.s_id,a.s_name,SUM(case c.c_name when '語文' then b.s_score else 0 end) as '語文',SUM(case c.c_name when '數(shù)學(xué)' then b.s_score else 0 end) as '數(shù)學(xué)',SUM(case c.c_name when '英語' then b.s_score else 0 end) as '英語',SUM(b.s_score) as '總分'from student a left join score b on a.s_id = b.s_id left join course c on b.c_id = c.c_id GROUP BY a.s_id,a.s_name -- 36、查詢?nèi)魏我婚T課程成績在70分以上的姓名、課程名稱和分?jǐn)?shù)； select a.s_name,b.c_name,c.s_score from course b left join score c on b.c_id = c.c_idleft join student a on a.s_id=c.s_id where c.s_score>=70 -- 37、查詢不及格的課程select a.s_id,a.c_id,b.c_name,a.s_score from score a left join course b on a.c_id = b.c_idwhere a.s_score<60 --38、查詢課程編號為01且課程成績在80分以上的學(xué)生的學(xué)號和姓名； select a.s_id,b.s_name from score a LEFT JOIN student b on a.s_id = b.s_idwhere a.c_id = '01' and a.s_score>80 -- 39、求每門課程的學(xué)生人數(shù) select count(*) from score GROUP BY c_id; -- 40、查詢選修"張三"老師所授課程的學(xué)生中，成績最高的學(xué)生信息及其成績-- 查詢老師id select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='張三'-- 查詢最高分（可能有相同分?jǐn)?shù)）select MAX(s_score) from score where c_id='02'-- 查詢信息select a.*,b.s_score,b.c_id,c.c_name from student aLEFT JOIN score b on a.s_id = b.s_idLEFT JOIN course c on b.c_id=c.c_idwhere b.c_id =(select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='張三')and b.s_score in (select MAX(s_score) from score where c_id='02') -- 41、查詢不同課程成績相同的學(xué)生的學(xué)生編號、課程編號、學(xué)生成績 select DISTINCT b.s_id,b.c_id,b.s_score from score a,score b where a.c_id != b.c_id and a.s_score = b.s_score -- 42、查詢每門功成績最好的前兩名 -- 牛逼的寫法select a.s_id,a.c_id,a.s_score from score awhere (select COUNT(1) from score b where b.c_id=a.c_id and b.s_score>=a.s_score)<=2 ORDER BY a.c_id -- 43、統(tǒng)計(jì)每門課程的學(xué)生選修人數(shù)（超過5人的課程才統(tǒng)計(jì)）。要求輸出課程號和選修人數(shù)，查詢結(jié)果按人數(shù)降序排列，若人數(shù)相同，按課程號升序排列 select c_id,count(*) as total from score GROUP BY c_id HAVING total>5 ORDER BY total,c_id ASC -- 44、檢索至少選修兩門課程的學(xué)生學(xué)號 select s_id,count(*) as sel from score GROUP BY s_id HAVING sel>=2 -- 45、查詢選修了全部課程的學(xué)生信息 select * from student where s_id in( select s_id from score GROUP BY s_id HAVING count(*)=(select count(*) from course)) --46、查詢各學(xué)生的年齡-- 按照出生日期來算，當(dāng)前月日 < 出生年月的月日則，年齡減一select s_birth,(DATE_FORMAT(NOW(),'%Y')-DATE_FORMAT(s_birth,'%Y') - (case when DATE_FORMAT(NOW(),'%m%d')>DATE_FORMAT(s_birth,'%m%d') then 0 else 1 end)) as agefrom student; -- 47、查詢本周過生日的學(xué)生select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))=WEEK(s_birth)select * from student where YEARWEEK(s_birth)=YEARWEEK(DATE_FORMAT(NOW(),'%Y%m%d'))select WEEK(DATE_FORMAT(NOW(),'%Y%m%d')) -- 48、查詢下周過生日的學(xué)生select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =WEEK(s_birth) -- 49、查詢本月過生日的學(xué)生select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d')) =MONTH(s_birth) -- 50、查詢下月過生日的學(xué)生select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =MONTH(s_birth)

總結(jié)

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