09)查询学过「张三」老师授课的同学的信息
SELECTs.*,c.cname,t.tnameFROMt_mysql_teacher t,t_mysql_student s,t_mysql_course c,t_mysql_score scWHEREt.tid=c.tid and c.cid=sc.cid and sc.sid=s.sid and tname = '张三'
10)查询没有学全所有课程的同学的信息
SELECTs.sid,s.sname,count(sc.score) nFROMt_mysql_score sc,t_mysql_student sWHEREsc.sid=s.sidGROUP BYs.sid,s.snameHAVINGn<(select count(c.cid) from t_mysql_course c )
11)查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT s.* FROM t_mysql_student s where s.sid not in(SELECTsc.sidFROMt_mysql_teacher t,t_mysql_course c,t_mysql_score scWHEREt.tid=c.tid and c.cid=sc.cid and t.tname='张三'GROUP BYsc.sid)
12)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
SELECTs.sid,s.sname,ROUND(AVG(sc.score)) 平均成绩,COUNT(sc.cid) nFROMt_mysql_student s,t_mysql_score scWHEREs.sid=sc.sid and sc.score<60GROUP BYs.sid,s.snameHAVINGn>=2
13)检索" 01 "课程分数小于 60,按分数降序排列的学生信息
SELECTs.*FROMt_mysql_score sc,t_mysql_student sWHEREsc.sid=s.sid and sc.score<60 and cid='01'ORDER BY sc.score DESC
14)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
s.sid,s.sname,round(AVG(sc.score),2) avgNum ,
max(case when sc.cid='01' then sc.score end)语文,
max(case when sc.cid='02' then sc.score end)数学,
max(case when sc.cid='03' then sc.score end)英语
FROM
t_mysql_score sc,t_mysql_student s,t_mysql_course c
WHEREsc.sid=s.sid and sc.cid=c.cid
GROUP BY
s.sid,s.sname
ORDER BY avgNum desc
15)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
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
SELECTc.cid,c.cname,count(sc.sid) 人数,max(sc.score) 最高分,min(sc.score) 最低分,ROUND(avg(sc.score),2) 平均分,CONCAT(ROUND(sum(if(sc.score>=60,1,0))/(SELECT COUNT(1) from t_mysql_student)*100 ,2),'%') 及格率,CONCAT(ROUND(sum(if(sc.score>=70 and sc.score<80,1,0))/(SELECT COUNT(1) from t_mysql_student)*100 ,2),'%') 中等率,CONCAT(ROUND(sum(if(sc.score>=80 and sc.score<90,1,0))/(SELECT COUNT(1) from t_mysql_student)*100 ,2),'%') 优良率,CONCAT(ROUND(sum(if(sc.score>=90,1,0))/(SELECT COUNT(1) from t_mysql_student)*100 ,2),'%') 优秀率
FROMt_mysql_score scLEFT JOIN t_mysql_course c ON sc.cid = c.cid
GROUP BYc.cid,c.cname