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- 建表
--学生表
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`)
);
--课程表
CREATE TABLE `Course`(
`c_id` VARCHAR(20),
`c_name` VARCHAR(20) NOT NULL DEFAULT '',
`t_id` VARCHAR(20) NOT NULL,
PRIMARY KEY(`c_id`)
);
--教师表
CREATE TABLE `Teacher`(
`t_id` VARCHAR(20),
`t_name` VARCHAR(20) NOT NULL DEFAULT '',
PRIMARY KEY(`t_id`)
);
--成绩表
CREATE TABLE `Score`(
`s_id` VARCHAR(20),
`c_id` VARCHAR(20),
`s_score` INT(3),
PRIMARY KEY(`s_id`,`c_id`)
);
- 插入数据
--插入学生表测试数据
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');
--课程表测试数据
insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');--教师表测试数据
insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');--成绩表测试数据
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);
- 题目
-- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
SELECT s.*,a.s_score,b.s_score FROM Student s,Score a, Score b
WHERE s.s_id=a.s_id AND s.s_id=b.s_id AND a.c_id=01 AND b.c_id=02
AND a.s_score>b.s_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
SELECT s.*,a.s_score,b.s_score FROM Student s,Score a, Score b
WHERE s.s_id=a.s_id AND s.s_id=b.s_id AND a.c_id=01 AND b.c_id=02
AND a.s_score<b.s_score;-- 3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
SELECT st.s_id,st.s_name,AVG(IFNULL(sc.s_score,0)) a
FROM Student st LEFT JOIN Score sc ON st.s_id=sc.s_id GROUP BY st.s_id HAVING a>=60;-- 4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
-- (包括有成绩的和无成绩的)SELECT st.s_id,st.s_name,AVG(IFNULL(sc.s_score,0)) a
FROM Student st LEFT JOIN Score sc ON st.s_id=sc.s_id GROUP BY st.s_id HAVING a<60;-- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
SELECT st.s_id,st.s_name, SUM(sc.c_id) "选课总数",SUM(sc.s_score) "总成绩" FROM Student st LEFT JOIN Score sc
ON st.s_id=sc.s_id GROUP BY st.s_id;
-- 6、查询"李"姓老师的数量
SELECT COUNT(*) FROM teacher WHERE t_name LIKE '李%';-- 7、查询学过"张三"老师授课的同学的信息
SELECT st.* FROM Student st INNER JOIN (Score sc,Course cc, Teacher t)
ON st.s_id=sc.s_id AND sc.c_id=cc.c_id AND cc.t_id=t.t_id WHERE t.t_name='张三';-- 8、查询没学过"张三"老师授课的同学的信息
SELECT * FROM Student WHERE s_id NOT IN
(SELECT st.s_id FROM Student st INNER JOIN (Score sc,Course cc, Teacher t)
ON st.s_id=sc.s_id AND sc.c_id=cc.c_id AND cc.t_id=t.t_id WHERE t.t_name='张三');-- 9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
SELECT st.* FROM Student st INNER JOIN Score s ON st.s_id=s.s_id AND s.c_id='01'
INNER JOIN Score s1 ON st.s_id=s.s_id AND s1.c_id='02';-- 10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
SELECT st.* FROM Student st LEFT JOIN Score s ON st.s_id=s.s_id AND s.c_id='01'
LEFT JOIN Score s1 ON st.s_id=s1.s_id AND s1.c_id='02'
WHERE s.c_id='01' AND s1.c_id IS NULL;-- 11、查询没有学全所有课程的同学的信息
SELECT st.* FROM Student st LEFT JOIN Score sc ON st.s_id=sc.s_id GROUP BY st.s_id HAVING COUNT(c_id)<
(SELECT COUNT(*) FROM Course);-- 12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息
SELECT st.* FROM Student st LEFT JOIN Score sc ON st.s_id=sc.s_id
WHERE sc.c_id IN (SELECT c_id FROM Score WHERE s_id='01') AND st.s_id!='01' GROUP BY st.s_id;-- 13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
SELECT s.* FROM Student s INNER JOIN Score sc ON s.s_id=sc.s_id GROUP BY s.s_id HAVING COUNT(sc.c_id)=
(SELECT COUNT(*) FROM Score WHERE s_id='01') AND s.s_id!='01';-- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT stu.s_name FROM Student stu LEFT JOIN
(SELECT * FROM Teacher t INNER JOIN Course cc USING(t_id)
INNER JOIN Score sc USING(c_id) WHERE t.t_name='张三')stu1
ON stu.s_id=stu1.s_id WHERE stu1.t_id IS NULL;-- 15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
SELECT stu.s_id,stu.s_name,AVG(IFNULL(s_score,0)) FROM Student stu LEFT JOIN Score sc
ON stu.s_id=sc.s_id AND s_score<60 GROUP BY s_id HAVING COUNT(c_id)>=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 stu.* FROM Student stu INNER JOIN
(SELECT sc.s_id FROM Score sc WHERE sc.c_id='01' AND sc.s_score<60 ORDER BY sc.s_score DESC)bb
USING (s_id);-- 17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
SELECT * FROM Score sc INNER JOIN
(SELECT s_id ,AVG(s_score) '平均成绩' FROM Score GROUP BY s_id ORDER BY AVG(s_score) DESC)av
USING(s_id)-- 18.查询各科成绩最高分、最低分和平均分：以如下形式显示：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：>=90SELECT ss.c_id,c_name,MAX(s_score),MIN(s_score),AVG(s_score),
SUM(CASE WHEN s_score >=60 THEN 1 ELSE 0 END)/COUNT(ss.c_id) AS '及格率' ,
SUM(CASE WHEN s_score >=70 AND s_score<=80 THEN 1 ELSE 0 END)/COUNT(ss.c_id) AS '中等' ,
SUM(CASE WHEN s_score <=90 AND s_score>=80 THEN 1 ELSE 0 END)/COUNT(ss.c_id) AS '优良' ,
SUM(CASE WHEN s_score >=90 THEN 1 ELSE 0 END)/COUNT(ss.c_id) AS '优秀'
FROM Score ss LEFT JOIN Course cs ON ss.c_id=cs.c_id GROUP BY c_id-- 19、按各科成绩进行排序，并显示排名(实现不完全)
SET @yw=0;
SET @sx=0;
SET @yy=0;
SELECT aa.*,
(CASE c_id WHEN '01' THEN @yw:=@yw+1
WHEN '02' THEN @sx:=@sx+1 WHEN '03' THEN @yy:=@yy+1 ELSE 0 END) AS RAND FROM
(SELECT cc.c_name,cc.c_id,ss.s_id,ss.s_score FROM Course cc INNER JOIN Score ss
ON cc.c_id=ss.c_id ORDER BY cc.c_id,ss.s_score DESC)aa-- 20、查询学生的总成绩并进行排名
SELECT s_id,SUM(s_score) a FROM Score GROUP BY s_id ORDER BY a DESC
-- 21、查询不同老师所教不同课程平均分从高到低显示
SELECT t.t_name,cc.c_id, AVG(ss.s_score)a FROM Score ss INNER JOIN Course cc USING(c_id) INNER JOIN Teacher t USING(t_id)
GROUP BY ss.c_id ORDER BY a DESC;-- 22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
SELECT *
FROM (
(
SELECT c_id,s_id,s_score,
IF(@prec= c_id,@rank:=@rank+1,@rank:=1) AS 名次,@prec:= c_id
FROM score
ORDER BY c_id,s_score DESC
) t
)
WHERE 名次 = 2 OR 名次 = 3;-- 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 ss.c_id,cc.c_name,COUNT(s_id),
SUM(CASE WHEN ss.s_score>=85 THEN 1 ELSE 0 END) '[100-85]',
SUM(CASE WHEN ss.s_score>=70 AND ss.s_score<=85 THEN 1 ELSE 0 END) '[85*70]',
SUM(CASE WHEN ss.s_score>=60 AND ss.s_score<=70 THEN 1 ELSE 0 END) '[70-60]',
SUM(CASE WHEN ss.s_score<=60 THEN 1 ELSE 0 END) '[0-60]',
SUM(CASE WHEN ss.s_score>=85 THEN 1 ELSE 0 END)/COUNT(s_id) '[100-85]%',
SUM(CASE WHEN ss.s_score>=70 AND ss.s_score<=85 THEN 1 ELSE 0 END)/COUNT(s_id) '[85*70]%',
SUM(CASE WHEN ss.s_score>=60 AND ss.s_score<=70 THEN 1 ELSE 0 END)/COUNT(s_id) '[70-60]%',
SUM(CASE WHEN ss.s_score<=60 THEN 1 ELSE 0 END)/COUNT(s_id) '[0-60]%'
FROM Score ss LEFT JOIN Course cc ON ss.c_id=cc.c_id GROUP BY ss.c_id-- 24、查询学生平均成绩及其名次
SELECT aa.*,@rownum:=@rownum+1 AS rank FROM
(SELECT stu.*,AVG(IFNULL(sc.s_score,0)) FROM Student stu LEFT JOIN Score sc
ON stu.s_id=sc.s_id GROUP BY s_id ORDER BY AVG(sc.s_score) DESC)aa,
(SELECT @rownum:=0)r;-- 25、查询各科成绩前三名的记录
SELECT * FROM (
(SELECT c_id,s_id,s_score,
IF(@prec=c_id,@rank:=@rank+1,@rank:=1) AS 名次,@prec:=c_id
FROM Score ORDER BY c_id,s_score DESC)t
)
WHERE 名次 IN (1,2,3)-- 26、查询每门课程被选修的学生数
SELECT sc.c_id AS '课程',COUNT(sc.s_id) AS '人数' FROM Course cc,Score sc WHERE cc.c_id=sc.c_id GROUP BY cc.c_id
-- 27、查询出只有两门课程的全部学生的学号和姓名
SELECT stu.s_id,stu.s_name FROM Student stu LEFT JOIN Score sc USING(s_id) GROUP BY stu.s_id HAVING COUNT(sc.c_id)=2-- 28、查询男生、女生人数
SELECT COUNT(*) FROM student WHERE s_sex = '男'
SELECT COUNT(s_sex) a FROM student WHERE s_sex = '女'-- 29、查询名字中含有"风"字的学生信息
SELECT stu.* FROM Student stu WHERE stu.s_name LIKE '%风%'
-- 30、查询同名同性学生名单，并统计同名人数
SELECT st.s_name,st.s_sex,COUNT(*) FROM Student st GROUP BY st.s_name,st.s_sex HAVING COUNT(*)>1
-- 31、查询1990年出生的学生名单
SELECT st.s_id,st.s_name FROM Student st WHERE YEAR(st.s_birth)=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，按课程编号升序排列
SELECT cc.c_id, AVG(sc.s_score) FROM Course cc LEFT JOIN Score sc USING(c_id) GROUP BY cc.c_id ORDER BY AVG(sc.s_score) ,sc.c_id DESC
-- 33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
SELECT st.s_name, sc.s_id ,AVG(sc.s_score) FROM Student st LEFT JOIN Score sc USING(s_id) GROUP BY sc.s_id HAVING AVG(sc.s_score)>=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 st.s_name,sc.s_score FROM Student st LEFT JOIN Score sc USING(s_id) LEFT JOIN Course cc USING(c_id)
WHERE cc.c_name='数学' AND sc.s_score<60-- 35、查询所有学生的课程及分数情况；
SELECT st.s_id,st.s_name,cc.c_name,sc.s_score FROM Student st LEFT JOIN Score sc USING(s_id) LEFT JOIN Course cc USING(c_id)
-- 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 st.s_name,cc.c_name ,sc.s_score FROM Student st LEFT JOIN Score sc USING(s_id)
LEFT JOIN Course cc USING(c_id) WHERE sc.s_score>70-- 37、查询不及格的课程
SELECT st.s_name,cc.c_name ,sc.s_score FROM Student st LEFT JOIN Score sc USING(s_id)
LEFT JOIN Course cc USING(c_id) WHERE sc.s_score<60--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 st.s_id,st.s_name FROM Student st INNER JOIN Score sc USING(s_id)
WHERE sc.c_id='01' AND sc.s_score>=80-- 39、求每门课程的学生人数
SELECT cc.c_id, COUNT(*) FROM Course cc LEFT JOIN Score sc USING(c_id) LEFT JOIN Student st USING(s_id)
GROUP BY cc.c_id-- 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 st.*,sc.s_score FROM Student st INNER JOIN Score sc USING(s_id)
INNER JOIN (
SELECT sc.c_id,MAX(sc.s_score)AS maxcj FROM Score sc INNER JOIN Course cc USING(c_id)
INNER JOIN Teacher t USING(t_id) WHERE t.t_name='张三')tt ON sc.c_id=tt.c_id AND sc.s_score=tt.maxcj-- 41、查询不同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_id ,b.s_id,a.c_id,a.s_score FROM Score a,Score b WHERE a.c_id!=b.c_id AND a.s_score=b.s_score GROUP BY a.s_id
-- 42、查询每门功成绩最好的前两名
SELECT * FROM
(SELECT s_id,
IF(@prec=c_id,@rank:=@rank+1,@rank:=1) AS 名次,@prec:=c_id
FROM Score ORDER BY c_id,s_score DESC)t
WHERE 名次 IN (1,2)-- 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 sc.c_id,COUNT(*) FROM Score sc GROUP BY sc.c_id HAVING COUNT(*)>5
ORDER BY COUNT(*) DESC, sc.c_id;-- 44、检索至少选修两门课程的学生学号
SELECT sc.s_id FROM Score sc GROUP BY sc.s_id
HAVING COUNT(*)>=2-- 45、查询选修了全部课程的学生信息
SELECT st.* FROM Student st INNER JOIN Score sc USING(s_id) GROUP BY st.s_id
HAVING COUNT(*)=(SELECT COUNT(*) FROM Course )--46、查询各学生的年龄
SELECT st.s_name,(YEAR(CURDATE())-YEAR(st.s_birth)) AS '年龄' FROM Student st
-- 47、查询本周过生日的学生
SELECT * FROM Student st WHERE WEEK(CURDATE())=WEEK(st.s_birth)
-- 48、查询下周过生日的学生
SELECT * FROM Student st WHERE WEEK(CURDATE())=WEEK(st.s_birth)-1
-- 49、查询本月过生日的学生
SELECT * FROM Student st WHERE MONTH(CURDATE())=MONTH(st.s_birth)
-- 50、查询下月过生日的学生
SELECT * FROM Student st WHERE MONTH(CURDATE())+1=MONTH(st.s_birth)
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