建表语句
create table Student(sid 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 Course(cid varchar(10),cname varchar(10),tid 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(tid 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'); create table SC(sid varchar(10),cid 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); 3、表结构预览
--学生表 Student(SId,Sname,Sage,Ssex) --SId 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别 --课程表 Course(CId,Cname,TId) --CId 课程编号,Cname 课程名称,TId 教师编号 --教师表 Teacher(TId,Tname) --TId 教师编号,Tname 教师姓名 --成绩表 SC(SId,CId,score) --SId 学生编号,CId 课程编号,score 分数
题目 1、查询“01”课程比“02”课程成绩高的所有学生的学号； 2、查询平均成绩大于60分的同学的学号和平均成绩； 3、查询所有同学的学号、姓名、选课数、总成绩 4、查询姓“李”的老师的个数； 5、查询没学过“张三”老师课的同学的学号、姓名； 6、查询学过编号“01”并且也学过编号“02”课程的同学的学号、姓名； 7、查询学过“张三”老师所教的课的同学的学号、姓名； 8、查询课程编号“01”的成绩比课程编号“02”课程低的所有同学的学号、姓名； 9、查询所有课程成绩小于60分的同学的学号、姓名； 10、查询没有学全所有课的同学的学号、姓名； 11、查询至少有一门课与学号为“01”的同学所学相同的同学的学号和姓名； 12、查询和"01"号的同学学习的课程完全相同的其他同学的学号和姓名 13、把“SC”表中“张三”老师教的课的成绩都更改为此课程的平均成绩； 14、查询没学过"张三"老师讲授的任一门课程的学生姓名 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 16、检索"01"课程分数小于60，按分数降序排列的学生信息 17、按平均成绩从高到低显示所有学生的平均成绩 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 19、按各科平均成绩从低到高和及格率的百分数从高到低顺序 20、查询学生的总成绩并进行排名 21、查询不同老师所教不同课程平均分从高到低显示 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 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 24、查询学生平均成绩及其名次 25、查询各科成绩前三名的记录 26、查询每门课程被选修的学生数 27、查询出只选修了一门课程的全部学生的学号和姓名 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 31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime) 32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列 37、查询不及格的课程，并按课程号从大到小排列 38、查询课程编号为"01"且课程成绩在60分以上的学生的学号和姓名； 40、查询选修“张三”老师所授课程的学生中，成绩最高的学生姓名及其成绩 42、查询每门功课成绩最好的前两名 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 44、检索至少选修两门课程的学生学号 45、查询选修了全部课程的学生信息 46、查询各学生的年龄 47、查询本周过生日的学生 48、查询下周过生日的学生 49、查询本月过生日的学生 50、查询下月过生日的学生
答案 1、查询“01”课程比“02”课程成绩高的所有学生的学号；
select distinct t1.sid as sid from (select * from sc where cid='01')t1 left join (select * from sc where cid='02')t2 on t1.sid=t2.sid where t1.score>t2.score 2、查询平均成绩大于60分的同学的学号和平均成绩；
select sid ,avg(score) from sc group by sid having avg(score)>60 3、查询所有同学的学号、姓名、选课数、总成绩
select student.sid as sid ,sname ,count(distinct cid) course_cnt ,sum(score) as total_score from student left join sc on student.sid=sc.sid group by sid,sname 4、查询姓“李”的老师的个数；
select count(distinct tid) as teacher_cnt from teacher where tname like '李%' 5、查询没学过“张三”老师课的同学的学号、姓名；
select sid,sname from student where sid not in ( select sc.sid from teacher left join course on teacher.tid=course.tid left join sc on course.cid=sc.cid where teacher.tname='张三' ) 6、查询学过“01”并且也学过编号“02”课程的同学的学号、姓名；
select t.sid as sid ,sname from ( select sid ,count(if(cid='01',score,null)) as count1 ,count(if(cid='02',score,null)) as count2 from sc group by sid having count(if(cid='01',score,null))>0 and count(if(cid='02',score,null))>0 )t left join student on t.sid=student.sid 7、查询学过“张三”老师所教的课的同学的学号、姓名；
select student.sid ,sname from ( select distinct cid from course left join teacher on course.tid=teacher.tid where teacher.tname='张三' )course left join sc on course.cid=sc.cid left join student on sc.sid=student.sid group by student.sid,sname 8、查询课程编号“01”的成绩比课程编号“02”课程低的所有同学的学号、姓名；
select t1.sid,sname from ( select distinct t1.sid as sid from (select * from sc where cid='01')t1 left join (select * from sc where cid='02')t2 on t1.sid=t2.sid where t1.score>t2.score )t1 left join student on t1.sid=student.sid 9、查询所有课程成绩小于60分的同学的学号、姓名；
select t1.sid,sname from ( select sid,max(score) from sc group by sid having max(score<60) )t1 left join student on t1.sid=student.sid 10、查询没有学全所有课的同学的学号、姓名；
select t1.sid,sname from ( select count(cid),sid from sc group by sid having count(cid) < (select count(distinct cid) from course) )t1 left join student on t1.sid=student.sid 11、查询至少有一门课与学号为“01”的同学所学相同的同学的学号和姓名；
select distinct sc.sid from ( select cid from sc where sid='01' )t1 left join sc on t1.cid=sc.cid 12、查询和"01"号的同学学习的课程完全相同的其他同学的学号和姓名
#注意是和'01'号同学课程完全相同但非学习课程数相同的,这里我用左连接解决这个问题 select t1.sid,sname from ( select sc.sid ,count(distinct sc.cid) from ( select cid from sc where sid='01' )t1 #选出01的同学所学的课程 left join sc on t1.cid=sc.cid group by sc.sid having count(distinct sc.cid)= (select count(distinct cid) from sc where sid = '01') )t1 left join student on t1.sid=student.sid where t1.sid!='01' 13、把“SC”表中“张三”老师教的课的成绩都更改为此课程的平均成绩；
#暂跳过update题目 14、查询没学过"张三"老师讲授的任一门课程的学生姓名
select sname from student where sid not in ( select distinct sid from sc left join course on sc.cid=course.cid left join teacher on course.tid=teacher.tid where tname='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 t1.sid,sname,avg_score from ( select sid,count(if(score<60,cid,null)),avg(score) as avg_score from sc group by sid having count(if(score<60,cid,null)) >=2 )t1 left join student on t1.sid=student.sid 16、检索"01"课程分数小于60，按分数降序排列的学生信息
select sid,if(cid='01',score,100) from sc where if(cid='01',score,100)<60 order by if(cid='01',score,100) desc 17、按平均成绩从高到低显示所有学生的平均成绩
select sid,avg(score) from sc group by sid order by avg(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
select sc.cid ,cname ,max(score) as max_score ,min(score) as min_score ,avg(score) as avg_score ,count(if(score>=60,sid,null))/count(sid) as pass_rate from sc left join course on sc.cid=course.cid group by sc.cid 19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
#这里先按照平均成绩排序，再按照及格百分数排序，题目有点奇怪 select cid ,avg(score) as avg_score ,count(if(score>=60,sid,null))/count(sid) as pass_rate from sc group by cid order by avg_score,pass_rate desc 20、查询学生的总成绩并进行排名
select sid ,sum(score) as sum_score from sc group by sid order by sum_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 tid ,avg(score) as avg_score from course left join sc on course.cid=sc.cid group by tid order by avg_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 sid,rank_num,score,cid from ( select rank() over(partition by cid order by score desc) as rank_num ,sid ,score ,cid from sc )t where rank_num in (2,3) 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 sc.cid ,cname ,count(if(score between 85 and 100,sid,null))/count(sid) ,count(if(score between 70 and 85,sid,null))/count(sid) ,count(if(score between 60 and 70,sid,null))/count(sid) ,count(if(score between 0 and 60,sid,null))/count(sid) from sc left join course on sc.cid=course.cid group by sc.cid,cname 24、查询学生平均成绩及其名次
select sid ,avg_score ,rank() over (order by avg_score desc) from ( select sid ,avg(score) as avg_score from sc group by sid )t 25、查询各科成绩前三名的记录
select sid,cid,rank1 from ( select cid ,sid ,rank() over(partition by cid order by score desc) as rank1 from sc )t where rank1<=3 26、查询每门课程被选修的学生数
select count(sid) ,cid from sc group by cid 27、查询出只选修了一门课程的全部学生的学号和姓名
#只查出来sid即可，后面懒得交student表 select sid from sc group by sid having count(cid) =1 28、查询男生、女生人数
select ssex ,count(distinct sid) from student group by ssex 29、查询名字中含有"风"字的学生信息
select sid,sname from student where sname like '%风%' 30、查询同名同性学生名单，并统计同名人数
#题目有歧义，这套题的质量感觉有点差 select ssex ,sname ,count(sid) from student group by ssex,sname having count(sid)>=2 31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)
select sid,sname,sage from student where year(sage)=1990 32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
select cid,avg(score) as avg_score from sc group by cid order by avg_score,cid desc 37、查询不及格的课程，并按课程号从大到小排列
#有问题的题目 select cid,sid,score from sc where score<60 order by cid desc,sid 38、查询课程编号为"01"且课程成绩在60分以上的学生的学号和姓名；
select sid,cid,score from sc where cid='01' and score>60 40、查询选修“张三”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select sc.sid,sname,cname,score from sc left join course on sc.cid=course.cid left join teacher on course.tid=teacher.tid left join student on sc.sid=student.sid where tname='张三' order by score desc limit 1; 42、查询每门功课成绩最好的前两名
##感觉题目重复了 select cid,sid,rank1 from ( select cid ,sid ,rank() over(partition by cid order by score desc) as rank1 from sc )t where rank1 <=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 cid ,count(sid) as cnt from sc group by cid having cnt>=5 order by count(sid) desc,cid 44、检索至少选修两门课程的学生学号
select sid ,count(cid) from sc group by sid having count(cid)>=2 45、查询选修了全部课程的学生信息
#不太严谨，但实务中应该没问题，如需严谨见12题思路 select sid ,count(cid) from sc group by sid having count(cid)=(select count(distinct cid) from sc) 46、查询各学生的年龄
select sid,sname,year(curdate())-year(sage) as sage from student 47、查询本周过生日的学生
select sid,sname,sage from student where weekofyear(sage)=weekofyear(curdate()) 48、查询下周过生日的学生
select sid,sname,sage from student where weekofyear(sage) = weekofyear(date_add(curdate(),interval 1 week)) 49、查询本月过生日的学生
select sid,sname,sage from student where month(sage) = month(curdate()) 50、查询下月过生日的学生
select sid,sname,sage from student where month(date_sub(sage,interval 1 month)) = month(curdate())
来源：oschina
链接：https://my.oschina.net/u/4398200/blog/3336586