--1.学生表
Student(S,Sname,Sage,Ssex) --S 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
Course(C,Cname,T) --C --课程编号,Cname 课程名称,T 教师编号
--3.教师表
Teacher(T,Tname) --T 教师编号,Tname 教师姓名
--4.成绩表
SC(S,C,score) --S 学生编号,C 课程编号,score 分数
sql
--建立测试数据 create table Student( S varchar(10), Sname varchar(10), Sage datetime, Ssex nvarchar(10) ) ; insert into Student values('01' , '赵雷' , '1990-01-01' , '男'); insert into Student values('02' , '钱电' , '1990-12-21' , '男'); insert into Student values('03' , '孙风' , '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' , '吴兰' , '1992-03-01' , '女'); insert into Student values('07' , '郑竹' , '1989-07-01' , '女'); insert into Student values('08' , '王菊' , '1990-01-20' , '女'); create table SC( S varchar(10), C varchar(10), score decimal(18,1) ); insert into SC values('01' , '01' , 80); insert into SC values('01' , '02' , 90); insert into SC values('01' , '03' , 99); insert into SC values('02' , '01' , 70); insert into SC values('02' , '02' , 60); insert into SC values('02' , '03' , 80); insert into SC values('03' , '01' , 80); insert into SC values('03' , '02' , 80); insert into SC values('03' , '03' , 80); insert into SC values('04' , '01' , 50); insert into SC values('04' , '02' , 30); insert into SC values('04' , '03' , 20); insert into SC values('05' , '01' , 76); insert into SC values('05' , '02' , 87); insert into SC values('06' , '01' , 31); insert into SC values('06' , '03' , 34); insert into SC values('07' , '02' , 89); insert into SC values('07' , '03' , 98);
create table Course( C varchar(10), Cname varchar(10), T varchar(10) ); insert into Course values('01' , '语文' , '02'); insert into Course values('02' , '数学' , '01'); insert into Course values('03' , '英语' , '03'); create table Teacher( T varchar(10), Tname varchar(10) ); insert into Teacher values('01' , '张三'); insert into Teacher values('02' , '李四'); insert into Teacher values('03' , '王五');
--一、查询"01"课程比"02"课程成绩高的学生的信息及课程分数学习
SELECT a.* ,b.score AS '01分数' ,c.score AS '02分数' FROM student a INNER JOIN sc b ON a.s=b.s AND b.c='01' INNER JOIN sc c ON a.s=c.s AND c.c='02' WHERE b.score > c.score ;
--2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
--3、查询平均成绩大于等于60分的同窗的学生编号和学生姓名和平均成绩测试
SELECT a.s ,a.sname ,AVG(b.score) AS avgnum FROM student a INNER JOIN sc b ON a.s=b.s GROUP BY a.s,a.sname HAVING AVG(b.score)>60 ;
--4、查询平均成绩小于60分的同窗的学生编号和学生姓名和平均成绩
--5、查询全部同窗的学生编号、学生姓名、选课总数、全部课程的总成绩spa
--6、查询"李"姓老师的数量 code
SELECT COUNT(1) FROM teacherWHERE tname LIKE '李%' ;
--7、查询学过"张三"老师授课的同窗的信息 排序
SELECT a.* FROM student a INNER JOIN sc b ON a.s=b.s INNER JOIN course c ON b.c=c.c INNER JOIN teacher d ON c.t=d.t WHERE d.tname='张三' GROUP BY 1,2,3,4 ; --方法2 SELECT a.* FROM student a LEFT JOIN ( SELECT a.* FROM student a INNER JOIN sc b ON a.s=b.s INNER JOIN course c ON b.c=c.c INNER JOIN teacher d ON c.t=d.t WHERE d.tname='张三' GROUP BY 1,2,3,4 )b ON a.s=b.s WHERE b.s IS NOT NULL ;
--8、查询没学过"张三"老师授课的同窗的信息 ci
SELECT a.* FROM student a LEFT JOIN sc b ON a.s=b.s WHERE NOT EXISTS( SELECT * FROM course aa INNER JOIN teacher b ON aa.t=b.t INNER JOIN sc c ON aa.c=c.c WHERE b.tname='张三' AND c.s=a.s ) GROUP BY 1,2,3,4 ;
--9、查询学过编号为"01"而且也学过编号为"02"的课程的同窗的信息数学
SELECT a.* FROM student a INNER JOIN sc b ON a.s=b.s AND b.c='01' INNER JOIN sc c ON a.s=c.s AND c.c='02' ;
--10、查询学过编号为"01"可是没有学过编号为"02"的课程的同窗的信息table
select * from student a left join sc b on a.s=b.s and b.c='01' left join sc c on a.s=c.s and c.c='02' where b.c='01' and c.c is null ;
--11、查询没有学全全部课程的同窗的信息 class
SELECT a.* FROM student a LEFT JOIN sc b ON a.s=b.s LEFT JOIN (SELECT COUNT(1) anumFROM course) c ON 1=1 GROUP BY 1,2,3,4 HAVING MAX(c.anum)>COUNT(b.c) ;
--12、查询至少有一门课与学号为"01"的同窗所学相同的同窗的信息
SELECT a.* FROM student a INNER JOIN sc b ON a.s=b.s WHERE EXISTS( SELECT 1 FROM sc WHERE s='01' AND c=b.c ) GROUP BY 1,2,3,4 ;
--13、查询和"01"号的同窗学习的课程彻底相同的其余同窗的信息
SELECT a.s,a.sname,a.sage,a.ssex FROM (SELECT a.*,COUNT(b.c) ASsnum FROM student a INNER JOIN sc b ON a.s=b.s WHERE EXISTS( SELECT 1 FROM scWHERE s='01' AND c=b.c ) GROUP BY 1,2,3,4)a INNER JOIN (SELECTa.*,COUNT(b.c) AS anum FROM student a INNER JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4)b ON a.s=b.s INNER JOIN (SELECT COUNT(1) ASnum1 FROM sc WHERE s='01')c ON 1=1 WHERE a.snum=b.anum ANDa.snum=c.num1 ; --方法二 SELECT a.* ,COUNT(b.c) AS anum ,SUM(CASE WHEN EXISTS(SELECT 1 FROM sc WHERE s='01' AND c=b.c)THEN 1 ELSE 0 END) AS snum ,MAX(c.num1) AS num1 FROM student a INNER JOIN sc b ON a.s=b.s INNER JOIN (SELECT COUNT(1) ASnum1 FROM sc WHERE s='01')c ON 1=1 GROUP BY 1,2,3,4 HAVING anum=snum AND anum=num1 ;
--14、查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT a.* FROM student a LEFT JOIN( SELECT a.s FROM student a LEFT JOIN sc b ON a.s=b.s LEFT JOIN course c ON b.c=c.c LEFT JOIN teacher d ON c.t=d.t AND d.tname='张三' WHERE d.t IS NOT NULL )b ON a.s=b.s WHERE b.s IS NULL ;
--15、查询两门及其以上不及格课程的同窗的学号,姓名及其平均成绩
SELECT a.s ,a.sname ,AVG(b.score) FROM student a INNER JOIN sc b ON a.s=b.s GROUP BY 1,2 HAVING SUM(CASE WHENb.score>=60 THEN 0 ELSE 1 END)>=2 ;
--16、检索"01"课程分数小于60,按分数降序排列的学生信息
SELECT a.* ,b.score FROM student a INNER JOIN sc b ON a.s=b.s WHERE b.c='01' AND b.score < 60 ORDER BY b.score DESC ;
--17、按平均成绩从高到低显示全部学生的全部课程的成绩以及平均成绩
SELECT a.* ,SUM(CASE WHEN b.c='01' THEN b.scoreELSE 0 END) AS s01 ,SUM(CASE WHEN b.c='02' THEN b.scoreELSE 0 END) AS s02 ,SUM(CASE WHEN b.c='03' THEN b.score ELSE0 END) AS s03 ,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.score END) avs FROM student a LEFT JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4 ORDER BY avs DESC ;
--18、查询各科成绩最高分、最低分和平均分:以以下形式显示:课程ID,课程name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
--及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
SELECT a.c ,a.cname ,MAX(b.score) ,MIN(b.score) ,AVG(b.score) ,SUM(CASE WHEN b.score>=60 THEN 1 ELSE 0 END)/COUNT(1) ,SUM(CASE WHEN b.score>=70 AND b.score<80 THEN 1 ELSE 0 END)/COUNT(1) ,SUM(CASE WHEN b.score>=80 AND b.score<90 THEN 1 ELSE 0 END)/COUNT(1) ,SUM(CASE WHEN b.score>=90 THEN 1 ELSE 0 END)/COUNT(1) FROM course a INNER JOIN sc b ON a.c=b.c GROUP BY 1,2 ;
--19、按各科成绩进行排序,并显示排名
SET @rn:=0; SELECT a.*,@rn:=@rn+1 FROM( SELECT a.*,b.score FROM course a INNER JOIN sc b ON a.c=b.c WHERE a.c='01' ORDER BY b.c,score DESC )a ;
--20、查询学生的总成绩并进行排名
SELECT a.* ,COUNT(b.c)+1 asall FROM sc a LEFT JOIN sc b ON a.c=b.c AND a.score < b.score GROUP BY 1,2,3 ORDER BY a.c,asall ;
--21、查询不一样老师所教不一样课程平均分从高到低显示
SELECT a.* ,b.cname ,AVG(c.score) ascore FROM teacher a INNER JOIN course b ON a.t=b.t INNER JOIN sc c ON b.c=c.c GROUP BY 1,2,3 ORDER BY ascore DESC ;
--22、查询全部课程的成绩第2名到第3名的学生信息及该课程成绩
SELECT a.*,b.cname,b.score FROM student a INNER JOIN ( SELECT a.* ,c.cname ,COUNT(b.c)+1 AStp FROM sc a LEFT JOIN sc b ON a.c=b.c AND a.score<b.score LEFT JOIN course c ON a.c=c.c GROUP BY 1,2,3,4 HAVING COUNT(b.c)+1 IN(2,3) ORDER BY a.c,tp)b ON a.s=b.s ;
--23、统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
SELECT a.c ,a.cname ,SUM(CASE WHEN b.score<=100 AND b.score>85 THEN 1 ELSE 0 END) AS '[100-85]' ,SUM(CASE WHEN b.score<=85 AND b.score>70 THEN 1 ELSE 0 END) AS '[85-70]' ,SUM(CASE WHEN b.score<=70 AND b.score>60 THEN 1 ELSE 0 END) AS '[70-60]' ,SUM(CASE WHEN b.score<=60 AND b.score>0 THEN 1 ELSE 0 END) AS '[60-0]' ,SUM(CASE WHEN b.score<=100 AND b.score>85 THEN 1 ELSE 0 END)/COUNT(1) AS '[100-85]%' ,SUM(CASE WHEN b.score<=85 AND b.score>70 THEN 1 ELSE 0 END)/COUNT(1) AS '[85-70]%' ,SUM(CASE WHEN b.score<=70 AND b.score>60 THEN 1 ELSE 0 END)/COUNT(1) AS '[70-60]%' ,SUM(CASE WHEN b.score<=60 AND b.score>0 THEN 1 ELSE 0 END)/COUNT(1) AS '[60-0]%' FROM course a INNER JOIN sc b ON a.c=b.c GROUP BY 1,2 ;
--24、查询学平生均成绩及其名次
SELECT a.* ,COUNT(b.s)+1 FROM ( SELECT a.*,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.scoreEND) AS ascore FROM student a LEFT JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4 )a LEFT JOIN( SELECT a.*,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.scoreEND) AS ascore FROM student a LEFT JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4 )b ON a.ascore<b.ascore GROUP BY 1,2,3,4,5 ;
--25、查询各科成绩前三名的记录
SELECT a.*,COUNT(b.c)+1 ASascore FROM sc a LEFT JOIN sc b ON a.c=b.c AND a.score<b.score GROUP BY 1,2,3 HAVING ascore<=3 ORDER BY a.c,ascore ;
--26、查询每门课程被选修的学生数
SELECT a.* ,COUNT(b.s) FROM course a LEFT JOIN sc b ON a.c=b.c GROUP BY 1,2,3 ;
--27、查询出只有两门课程的所有学生的学号和姓名
SELECT a.* ,COUNT(b.c) FROM student a LEFT JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4 HAVING COUNT(b.c)=2 ;
--28、查询男生、女生人数
--29、查询名字中含有"风"字的学生信息
--30、查询同名同性学生名单,并统计同名人数
SELECT sname ,ssex ,COUNT(1) FROM student GROUP BY 1,2 HAVING COUNT(1) > 1 ;
--31、查询1990年出生的学生名单(注:Student表中Sage列的类型是datetime)
SELECT * FROM student WHERE YEAR(sage)=1990 ;
--32、查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号
SELECT a.* ,AVG(b.score) ascore FROM course a LEFT JOIN sc b ON a.c=b.c GROUP BY 1,2,3 ORDER BYascore DESC,a.c ;
--33、查询平均成绩大于等于85的全部学生的学号、姓名和平均成绩
SELECT a.* ,AVG(b.score) ascore FROM student a LEFT JOIN sc b ON a.s=b.s GROUP BY 1,2,3,4 HAVING ascore>=85 ;
--34、查询课程名称为"数学",且分数低于60的学生姓名和分数
SELECT c.* FROM course a LEFT JOIN sc b ON a.c=b.c LEFT JOIN student c ON b.s=c.s WHERE a.cname='数学' AND b.score < 60 ;
--35、查询全部学生的课程及分数状况;
SELECT * FROM sc a INNER JOIN student b ON a.s=b.s INNER JOIN course c ON a.c=c.c ;
--36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数;
SELECT b.sname ,c.cname ,a.score FROM sc a INNER JOIN student b ON a.s=b.s INNER JOIN course c ON a.c=c.c WHERE a.score > 70 ;
--37、查询不及格的课程
--38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名;
SELECT a.* FROM student a INNER JOIN sc b ON a.s=b.s WHERE b.c='01' AND b.score > 80 ;
--39、求每门课程的学生人数
--40、查询选修"张三"老师所授课程的学生中,成绩最高的学生信息及其成绩
SELECT a.*,b.score FROM student a INNER JOIN sc b ON a.s=b.s INNER JOIN( SELECT c.c ,MAX(c.score) ASmaxscore FROM teacher a INNER JOIN course b ON a.t=b.t INNER JOIN sc c ON b.c=c.c WHERE a.tname='张三' GROUP BY c)c ON b.c=c.c AND b.score=c.maxscore ;
--41、查询不一样课程成绩相同的学生的学生编号、课程编号、学生成绩
SELECT a.s ,a.c ,a.score FROM sc a INNER JOIN ( SELECT a.score ,b.s ,COUNT(1) FROM sc a INNER JOIN student b ON a.s=b.s GROUP BY a.score,b.s HAVING COUNT(1)>1 )b ON a.s=b.s AND a.score=b.score ; 方法二 SELECT a.* FROM sc a LEFT JOIN sc b ON a.s=b.s AND a.score=b.score AND a.c <> b.c GROUP BY 1,2,3 HAVING COUNT(b.s) > 0 ;
--42、查询每门功成绩最好的前两名
--43、统计每门课程的学生选修人数(超过5人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列
SELECT a.c ,COUNT(1) AS pnum FROM sc a GROUP BY 1 HAVING pnum > 5 ORDER BY pnum DESC,a.c ;
--44、检索至少选修两门课程的学生学号
--45、查询选修了所有课程的学生信息
--46、查询各学生的年龄
SELECT a.*,YEAR(CURDATE())-YEAR(a.sage) FROM student a ;
--47、查询本周过生日的学生
SELECT a.* FROM student a WHERE CONCAT(MONTH(a.sage),DAY(a.sage))>=CONCAT(MONTH(SUBDATE(CURDATE(),WEEKDAY(CURDATE()))),DAY(SUBDATE(CURDATE(),WEEKDAY(CURDATE())))) AND CONCAT(MONTH(a.sage),DAY(a.sage))<=CONCAT(MONTH(SUBDATE(CURDATE(),WEEKDAY(CURDATE())-6)),DAY(SUBDATE(CURDATE(),WEEKDAY(CURDATE())-6))) ;
--48、查询下周过生日的学生
--49、查询本月过生日的学生
SELECT a.* FROM student a WHERE MONTH(a.sage)=MONTH(CURDATE()) ;
--50、查询下月过生日的学生
SELECT a.*FROM student a WHERE MONTH(a.sage)=MONTH(CURDATE())+1 ;
有些没有答案的,是由于和上面的差很少,偷个懒。。。。