– 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 st.*, sc.s_score AS ‘语文’, sc2.s_score AS ‘数学’
FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id AND sc.c_id=‘01’ LEFT JOIN score sc2 ON sc2.s_id=st.s_id AND sc2.c_id=‘02’ WHERE sc.s_score>sc2.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 st.*, sc.s_score AS ‘语文’, sc2.s_score AS ‘数学’
FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id AND sc.c_id=‘01’ LEFT JOIN score sc2 ON sc2.s_id=st.s_id AND sc2.c_id=‘02’ WHERE sc.s_score < sc2.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, ROUND (AVG(sc.s_score),2)
FROM student st
JOIN score sc ON st.s_id=sc.s_id
GROUP BY st.s_id HAVING AVG(sc.s_score)>=60;
SELECT
st.s_id, st.s_name, ROUND(AVG(sc.s_score),2)
FROM student st
LEFT JOIN score sc ON sc.s_id=st.s_id
GROUP BY st.s_id HAVING AVG(sc.s_score)>=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, CASE WHEN AVG(sc.s_score) IS NULL THEN '无' ELSE ROUND (AVG(sc.s_score) ,2) END AS '平均分'FROM student st
LEFT JOIN score sc
ON sc.s_id=st.s_id
GROUP BY st.s_id
HAVING AVG(sc.s_score)<60
OR AVG(sc.s_score) IS NULL
– 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, COUNT(sc.c_id),
CASE WHEN SUM(sc.s_score) IS NULL THEN 0.00 ELSE ROUND(SUM(sc.s_score),2) END AS '总成绩'FROM student st
LEFT JOIN score sc
ON sc.s_id=st.s_id
GROUP BY st.s_id
– 6、查询"李"姓老师的数量 SELECT COUNT(1) FROM teacher t
WHERE t.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
LEFT JOIN score sc ON sc.s_id=st.s_id
LEFT JOIN course c ON c.c_id=sc.c_id
LEFT JOIN teacher t ON t.t_id=c.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 s.* FROM student s WHERE s.s_id NOT IN(
SELECT st.s_id FROM student st
LEFT JOIN score sc ON sc.s_id=st.s_id
LEFT JOIN course c ON c.c_id=sc.c_id
LEFT JOIN teacher t ON t.t_id=c.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 sc ON sc.s_id=st.s_id AND sc.c_id=‘01’
WHERE st.s_id IN (
SELECT st2.s_id FROM student st2 INNER JOIN score sc2 ON sc2.s_id=st2.s_id AND sc2.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
INNER JOIN score sc ON sc.s_id=st.s_id AND sc.c_id=‘01’
WHERE st.s_id NOT IN (
SELECT st2.s_id FROM student st2 INNER JOIN score sc2 ON sc2.s_id=st2.s_id AND sc2.c_id=‘02’ )
– 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(sc.s_score)❤️ – 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 DISTINCT st.*
FROM student st
LEFT JOIN score sc ON sc.s_id=st.s_id WHERE sc.c_id IN ( SELECT sc2.c_id FROM student st2 LEFT JOIN score sc2 ON sc2.s_id=st2.s_id WHERE st2.s_id =‘01’
)
– 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 st.* FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id HAVING GROUP_CONCAT(sc.c_id) = ( SELECT GROUP_CONCAT(sc2.c_id) FROM student st2 LEFT JOIN score sc2 ON sc2.s_id=st2.s_id WHERE st2.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 st.s_name FROM student st WHERE st.s_id NOT IN ( SELECT sc.s_id FROM score sc INNER JOIN course c ON c.c_id=sc.c_id INNER JOIN teacher t ON t.t_id=c.t_id AND t.t_name=“张三” )
– 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 st.s_id,st.s_name,AVG(sc.s_score)
FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id WHERE sc.s_id IN
( SELECT sc.s_id FROM score sc WHERE sc.s_score<60 OR sc.s_score IS NULL GROUP BY sc.s_id HAVING COUNT(1)>=2 )
GROUP BY st.s_id
– 16、检索"01"课程分数小于60，按分数降序排列的学生信息
SELECT
st.*, sc.s_score
FROM student st
LEFT JOIN score sc
ON sc.s_id=st.s_id
WHERE sc.c_id=‘01’ AND sc.s_score<60
ORDER BY sc.s_score DESC ;
– 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 st.s_id,st.s_name, (CASE WHEN AVG(sc4.s_score) IS NULL THEN 0 ELSE AVG(sc4.s_score) END) “平均分”, (CASE WHEN sc.s_score IS NULL THEN 0 ELSE sc.s_score END) “语文”, (CASE WHEN sc2.s_score IS NULL THEN 0 ELSE sc2.s_score END) “数学”, (CASE WHEN sc3.s_score IS NULL THEN 0 ELSE sc3.s_score END) “英语” FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id AND sc.c_id=“01” LEFT JOIN score sc2 ON sc2.s_id=st.s_id AND sc2.c_id=“02” LEFT JOIN score sc3 ON sc3.s_id=st.s_id AND sc3.c_id=“03” LEFT JOIN score sc4 ON sc4.s_id=st.s_id GROUP BY st.s_id ORDER BY AVG(sc4.s_score) DESC
– 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：>=90
SELECT c.c_id,c.c_name,MAX(sc.s_score) “最高分”,MIN(sc.s_score) “最低分”,AVG(sc.s_score) “平均分” ,((SELECT COUNT(s_id) FROM score WHERE s_score>=60 AND c_id=c.c_id )/(SELECT COUNT(s_id) FROM score WHERE c_id=c.c_id)) “及格率” ,((SELECT COUNT(s_id) FROM score WHERE s_score>=70 AND s_score<80 AND c_id=c.c_id )/(SELECT COUNT(s_id) FROM score WHERE c_id=c.c_id)) “中等率” ,((SELECT COUNT(s_id) FROM score WHERE s_score>=80 AND s_score<90 AND c_id=c.c_id )/(SELECT COUNT(s_id) FROM score WHERE c_id=c.c_id)) “优良率” ,((SELECT COUNT(s_id) FROM score WHERE s_score>=90 AND c_id=c.c_id )/(SELECT COUNT(s_id) FROM score WHERE c_id=c.c_id)) “优秀率” FROM course c LEFT JOIN score sc ON sc.c_id=c.c_id GROUP BY c.c_id
– 19、按各科成绩进行排序
SELECT * FROM (SELECT * FROM score WHERE c_id = ‘01’ ORDER BY s_score DESC LIMIT 0,100 ) a UNION ALL SELECT * FROM (SELECT * FROM score WHERE c_id = ‘02’ ORDER BY s_score DESC LIMIT 0,100) b UNION ALL SELECT * FROM (SELECT * FROM score WHERE c_id = ‘03’ ORDER BY s_score DESC LIMIT 0,100) c;
SELECT * FROM score ORDER BY c_id,s_score DESC
– 20、查询学生的总成绩并进行排名
SELECT st.s_id,st.s_name,(CASE WHEN SUM(sc.s_score) IS NULL THEN 0 ELSE SUM(sc.s_score) END) AS ‘总成绩’ FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id ORDER BY SUM(sc.s_score) 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_id,t.t_name,c.c_name,AVG(sc.s_score) FROM teacher t LEFT JOIN course c ON c.t_id=t.t_id LEFT JOIN score sc ON sc.c_id =c.c_id GROUP BY t.t_id ORDER BY AVG(sc.s_score) 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 t1.* FROM (SELECT st.*,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id =sc.c_id AND c.c_id=“01” ORDER BY sc.s_score DESC LIMIT 1,2) t1
UNION ALL
SELECT t2.* FROM (SELECT st.*,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id =sc.c_id AND c.c_id=“02” ORDER BY sc.s_score DESC LIMIT 1,2) t2
UNION ALL
SELECT t3.* FROM (SELECT st.*,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id =sc.c_id AND c.c_id=“03” ORDER BY sc.s_score DESC LIMIT 1,2) t3
– 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 c.c_id,c.c_name ,((SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id AND sc.s_score<=100 AND sc.s_score>80)/(SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id )) “100-85” ,((SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id AND sc.s_score<=85 AND sc.s_score>70)/(SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id )) “85-70” ,((SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id AND sc.s_score<=70 AND sc.s_score>60)/(SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id )) “70-60” ,((SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id AND sc.s_score<=60 AND sc.s_score>=0)/(SELECT COUNT(1) FROM score sc WHERE sc.c_id=c.c_id )) “60-0” FROM course c ORDER BY c.c_id
– 24、查询学生平均成绩及其名次 ;
SELECT st.s_id,st.s_name,ROUND((CASE WHEN AVG(sc.s_score) IS NULL THEN 0 ELSE AVG(sc.s_score) END),2) “avg” FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id ORDER BY AVG(sc.s_score) DESC
– 25、查询各科成绩前三名的记录 SELECT a.* FROM ( SELECT st.s_id,st.s_name,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=‘01’ ORDER BY sc.s_score DESC LIMIT 0,3) a UNION ALL SELECT b.* FROM ( SELECT st.s_id,st.s_name,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=‘02’ ORDER BY sc.s_score DESC LIMIT 0,3) b UNION ALL SELECT c.* FROM ( SELECT st.s_id,st.s_name,c.c_id,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=‘03’ ORDER BY sc.s_score DESC LIMIT 0,3) c – 26、查询每门课程被选修的学生数
SELECT c.c_id, c.c_name, COUNT(1) FROM course c LEFT JOIN score sc ON sc.c_id=c.c_id GROUP BY sc.c_id
– 27、查询出只有两门课程的全部学生的学号和姓名 SELECT st.s_id,st.s_name FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id GROUP BY st.s_id HAVING COUNT(1)=2 – 28、查询男生、女生人数 SELECT st.s_sex,COUNT(1) FROM student st GROUP BY st.s_sex – 29、查询名字中含有"风"字的学生信息 SELECT st.* FROM student st WHERE st.s_name LIKE “%风%”;
– 30、查询同名同性学生名单，并统计同名人数 SELECT st.*,COUNT(1) FROM student st GROUP BY st.s_name,st.s_sex HAVING COUNT(1)>1
– 31、查询1990年出生的学生名单 SELECT st.* FROM student st WHERE st.s_birth LIKE “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 c.c_id,c.c_name,AVG(sc.s_score) FROM course c INNER JOIN score sc ON sc.c_id=c.c_id GROUP BY c.c_id ORDER BY AVG(sc.s_score) DESC,c.c_id ASC
– 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_id,st.s_name,AVG(sc.s_score) FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.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_id,st.s_name,sc.s_score FROM student st INNER JOIN score sc ON sc.s_id=st.s_id AND sc.s_score<60 INNER JOIN course c ON c.c_id=sc.c_id AND c.c_name =“数学”
– 35、查询所有学生的课程及分数情况； SELECT st.s_id,st.s_name,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id LEFT JOIN course c ON c.c_id =sc.c_id ORDER BY st.s_id,c.c_name – 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 st2.s_id,st2.s_name,c2.c_name,sc2.s_score FROM student st2 LEFT JOIN score sc2 ON sc2.s_id=st2.s_id LEFT JOIN course c2 ON c2.c_id=sc2.c_id WHERE st2.s_id IN( SELECT st.s_id FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id HAVING MIN(sc.s_score)>=70) ORDER BY s_id
– 37、查询不及格的课程 SELECT st.s_id,c.c_name,st.s_name,sc.s_score FROM student st INNER JOIN score sc ON sc.s_id=st.s_id AND sc.s_score<60 INNER JOIN course c ON c.c_id=sc.c_id
– 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,sc.s_score FROM student st INNER JOIN score sc ON sc.s_id=st.s_id AND sc.c_id=“01” AND sc.s_score>=80
– 39、求每门课程的学生人数 SELECT c.c_id,c.c_name,COUNT(1) FROM course c INNER JOIN score sc ON sc.c_id=c.c_id GROUP BY c.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.*,c.c_name,sc.s_score,t.t_name FROM student st INNER JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id INNER JOIN teacher t ON t.t_id=c.t_id AND t.t_name=“张三” ORDER BY sc.s_score DESC LIMIT 0,1 – 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 st.s_id,st.s_name,sc.c_id,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id LEFT JOIN course c ON c.c_id=sc.c_id WHERE ( SELECT COUNT(1) FROM student st2 LEFT JOIN score sc2 ON sc2.s_id=st2.s_id LEFT JOIN course c2 ON c2.c_id=sc2.c_id WHERE sc.s_score=sc2.s_score AND c.c_id!=c2.c_id )>1
– 42、查询每门课程成绩最好的前两名 SELECT a.* FROM (SELECT st.s_id,st.s_name,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=“01” ORDER BY sc.s_score DESC LIMIT 0,2) a UNION ALL SELECT b.* FROM (SELECT st.s_id,st.s_name,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=“02” ORDER BY sc.s_score DESC LIMIT 0,2) b UNION ALL SELECT c.* FROM (SELECT st.s_id,st.s_name,c.c_name,sc.s_score FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id INNER JOIN course c ON c.c_id=sc.c_id AND c.c_id=“03” ORDER BY sc.s_score DESC LIMIT 0,2) c
– 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(1) FROM score sc LEFT JOIN course c ON c.c_id=sc.c_id GROUP BY c.c_id HAVING COUNT(1)>5 ORDER BY COUNT(1) DESC,sc.c_id ASC
– 44、检索至少选修两门课程的学生学号 SELECT st.s_id FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id HAVING COUNT(1)>=2
– 45、查询选修了全部课程的学生信息
SELECT st.* FROM student st LEFT JOIN score sc ON sc.s_id=st.s_id GROUP BY st.s_id HAVING COUNT(1)=(SELECT COUNT(1) FROM course)
