SQL高级查询

t_student(sid,sname,sage,ssex) 学生表 
t_course(cid,cname,tid) 课程表 
t_score( scid,sid,cid,grade) 成绩表 
t_teacher(tid,tname) 教师表

CREATE TABLE `t_student` (  `sid` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键',  `sname` varchar(16) NOT NULL COMMENT '学生姓名',  `sage` int(11) DEFAULT NULL COMMENT '年龄',  `sex` char(1) DEFAULT NULL COMMENT '性别（0：女，1：男）',  PRIMARY KEY (`sid`)) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8

-- ------------------------------ Records of t_student-- ----------------------------INSERT INTO t_student VALUES ('1', 'Smile', '22', '1');INSERT INTO t_student VALUES ('2', 'Somnus', '20', '0');INSERT INTO t_student VALUES ('3', 'Smart', '22', '1');INSERT INTO t_student VALUES ('4', 'Storm', '24', '0');INSERT INTO t_student VALUES ('5', 'Simple', '23', '0');INSERT INTO t_student VALUES ('6', 'Storm', '22', '0');

CREATE TABLE `t_course` (  `cid` int(11) NOT NULL AUTO_INCREMENT,  `cname` varchar(32) NOT NULL COMMENT '课程名字',  `tid` int(11) DEFAULT NULL COMMENT '外键-教师ID',  PRIMARY KEY (`cid`),  KEY `fk_book` (`tid`),  CONSTRAINT `fk_book` FOREIGN KEY (`tid`) REFERENCES `t_teacher` (`tid`)) ENGINE=InnoDB DEFAULT CHARSET=utf8

-- ------------------------------ Records of t_course-- ----------------------------INSERT INTO t_course VALUES ('1', '企业管理', '1');INSERT INTO t_course VALUES ('2', '马克思', '2');INSERT INTO t_course VALUES ('3', 'UML', '3');INSERT INTO t_course VALUES ('4', '数据库', '4');INSERT INTO t_course VALUES ('5', 'JAVA', '5');

CREATE TABLE `t_score` (  `sid` int(11) NOT NULL DEFAULT '0' COMMENT '学生ID',  `cid` int(11) NOT NULL DEFAULT '0' COMMENT '课程ID',  `grade` int(3) DEFAULT NULL COMMENT '成绩',  PRIMARY KEY (`sid`,`cid`)) ENGINE=InnoDB DEFAULT CHARSET=utf8

-- ------------------------------ Records of t_score-- ----------------------------INSERT INTO t_score VALUES ('1', '1', '78');INSERT INTO t_score VALUES ('1', '2', '51');INSERT INTO t_score VALUES ('1', '3', '48');INSERT INTO t_score VALUES ('2', '1', '89');INSERT INTO t_score VALUES ('2', '2', '97');INSERT INTO t_score VALUES ('2', '3', '77');INSERT INTO t_score VALUES ('2', '4', '99');INSERT INTO t_score VALUES ('2', '5', '83');INSERT INTO t_score VALUES ('3', '2', '67');INSERT INTO t_score VALUES ('3', '3', '88');INSERT INTO t_score VALUES ('3', '4', '89');INSERT INTO t_score VALUES ('4', '1', '56');INSERT INTO t_score VALUES ('4', '2', '36');INSERT INTO t_score VALUES ('4', '4', '56');INSERT INTO t_score VALUES ('4', '5', '47');INSERT INTO t_score VALUES ('5', '2', '78');INSERT INTO t_score VALUES ('5', '3', '72');INSERT INTO t_score VALUES ('5', '4', '58');INSERT INTO t_score VALUES ('6', '1', '55');

CREATE TABLE `t_teacher` (  `tid` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键ID',  `tname` varchar(16) DEFAULT NULL COMMENT '教师名',  PRIMARY KEY (`tid`)) ENGINE=InnoDB DEFAULT CHARSET=utf8

-- ------------------------------ Records of t_teacher-- ----------------------------INSERT INTO t_teacher VALUES ('1', '叶平');INSERT INTO t_teacher VALUES ('2', 'teacher2');INSERT INTO t_teacher VALUES ('3', 'teacher3');INSERT INTO t_teacher VALUES ('4', 'teacher4');INSERT INTO t_teacher VALUES ('5', 'teacher5');

问题： 
1、查询“1”课程比“2”课程成绩高的所有学生的学号； 

select t1.sid from (select sid,grade from t_score where cid = '1') t1,(select sid,grade from t_score where cid = '2') t2 where t1.grade >t2.grade and t1.sid = t2.sid; ----------------------------------------------------------------------------------------------select t2.sid,t2.ca,t2.cb(    select t1.sid,sum(t1.ca) ca,sum(t1.cb) cb    from    (        select sid,        CASE WHEN cid = '1' THEN grade ELSE 0 END ca,        CASE WHEN cid = '2' THEN grade ELSE 0 END cb        from t_score    )t1    GROUP BY sid)t2where t2.ca > t2.cb

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(grade ) from t_score group by sid having avg(grade ) >60;  

3、查询所有同学的学号、姓名、选课数、总成绩； 

select t1.sid,t1.sname,count(t2.cid),sum(grade ) from t_student t1left join t_score t2on t1.sid = t2.sid group by t1.sid,t1.sname; 

4、查询姓“李”的老师的个数； 

select count(distinct(tname)) from t_teacher where tname like '李%'; 

5、查询没学过“叶平”老师课的同学的学号、姓名； 

select sid, sname from t_student     where sid not in (    select distinct(t1.sid) from t_score t1,t_course t2,t_teacher t3    where t1.cid = t2.cid and t3.tid = t2.tid and t3.tname = '叶平'); 

6、查询学过“1”并且也学过编号“2”课程的同学的学号、姓名； 

select t0.sid,t0.sname from t_student t0, t_score t1where t0.sid = t1.sid and t1.cid = '1'and exists(     select * from t_score t2 where  t2.sid = t1.sid and  t2.cid = '2'); 

7、查询学过“叶平”老师所教的所有课的同学的学号、姓名； 

select sid,sname from t_student where sid in (    select sid from  t_score t1 ,t_course t2,t_teacher t3    where t1.cid=t2.cid     and t3.tid=t2.tid     and t3.tname = '叶平'     group by sid     having count(t1.cid)=(    select count(cid) from t_course t1,t_teacher t2     where t2.tid=t1.tid and t2.tname = '叶平')); 

8、查询“1”课程比“2”课程成绩高的所有同学的学号、姓名； 

select sid,sname from (  select t1.sid,t1.sname,t2.grade ,  (    select grade from t_score t3 where t3.sid = t1.sid and t3.cid = '2'  ) grade2   from t_student t1, t_score t2 where t1.sid = t2.sid and t2.cid = '1') ttwhere grade2 < grade ; 

9、查询所有课程成绩小于60分的同学的学号、姓名； 

select sid,sname from t_student where sid not in (select t1.sid from t_student t1, t_score t2where t1.sid = t2.sid and t2.grade >60); 

10、查询没有学全所有课的同学的学号、姓名； 

select t1.sid,t1.sname from t_student t1, t_score t2    where t1.sid = t2.sid group by t1.sid,t1.sname having count(t2.cid) < (select count(cid) from t_course);

14、查询和“3”号的同学学习的课程完全相同的其他同学学号和姓名； 

select sid from t_score where cid in (select cid from t_score where sid = '3')     group by sid having count(*)=(select count(*) from t_score where sid = '3'); 

15、删除学习“叶平”老师课的  t_score表记录； 

delect t_score from t_course t1 ,t_teacher t2Where t1.cid = t2.cid and t1.tid = t2.tid and t2.tname = '叶平';

16、向  t_score表中插入一些记录，这些记录要求符合以下条件：没有上过编号“3”课程的同学学号、2 号课程的平均成绩； 

insert  t_score select sid,'2',(Select avg(grade ) from  t_score where cid = '2') from t_student where sid not in (Select sid from  t_score where cid = '2');

17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分 

SELECT sid as 学生ID,(SELECT grade  FROM   t_score WHERE sid=t.sid AND cid='4') AS 数据库,(SELECT grade  FROM   t_score WHERE sid=t.sid AND cid='1') AS 企业管理,(SELECT grade  FROM   t_score WHERE sid=t.sid AND cid='5') AS  JAVA,COUNT(*) AS 有效课程数, AVG(t.grade ) AS 平均成绩     FROM   t_score AS t     GROUP BY sid     ORDER BY avg(t.grade )

21、查询不同老师所教不同课程平均分从高到低显示 

SELECT max(t3.tid) AS 教师ID,MAX(t3.tname) AS 教师姓名,T2.cid AS 课程ID,MAX(t2.cname) AS 课程名称,AVG(grade ) AS 平均成绩     FROM t_score AS t1,t_course AS t2 ,t_teacher AS t3     where t1.cid = t2.cid and t2.tid = t3.tid GROUP BY t2.cid ORDER BY AVG(grade ) DESC ;

23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60] 

SELECT  t1.cid as 课程ID, t2.cname as 课程名称,SUM(CASE WHEN t1.grade  BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85],SUM(CASE WHEN t1.grade  BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70],SUM(CASE WHEN t1.grade  BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60],SUM(CASE WHEN t1.grade  < 60 THEN 1 ELSE 0 END) AS [60 -]     FROM  t_score t1,t_course t2 where t1.cid = t2.cid     GROUP BY t1.cid,t2.cname;

24、查询学生平均成绩及其名次 

SELECT 1+(SELECT COUNT( distinct avggrade )               FROM (SELECT sid,AVG(grade ) AS avggrade  FROM  t_score GROUP BY sid ) AS T1 WHERE avggrade  > T2.avggrade ) as 名次,sid as 学生学号,avggrade   FROM (SELECT sid,AVG(grade )as avggrade  FROM  t_score  GROUP BY sid ) AS T2     ORDER BY avggrade desc; 

26、查询每门课程被选修的学生数 

select cid,count(sid) from t_score 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 

select t1.sid,t2.sname,count(t1.cid) AS 选课数 from t_score t1,t_student t2where t1.sid=t2.sid group by t1.sid ,t2.sname having count(t1.cid)=1;  

28、查询男生、女生人数 

Select count(sex) as 男生人数 from t_student group by sex having sex='1';     Select count(sex) as 女生人数 from t_student group by sex having sex='0';

30、查询同名同性学生名单，并统计同名人数 

select sname,count(*) from t_student group by sname having count(*)>1;

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(grade ) from  t_score group by cid order by Avg(grade ),cid DESC

33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩 

select t1.sname, t2.sid ,avg(t2.grade ) from t_student t1, t_score t2     where t1.sid=t2.sid group by t2.sid,t1.sname having  avg(t2.grade )>85; 

34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数 

Select t1.sname,ifnull(t2.grade ,0) from t_student t1, t_score t2,t_course t3   where t2.sid = t1.sid and t2.cid = t3.cid and t3.cname='数据库'and  t2.grade <60; 

35、查询所有学生的选课情况； 

SELECT t1.sid, t1.cid,t2.sname,t3.cname FROM t_score t1,t_student t2,t_course t3    where t1.sid = t2.sid and t1.cid = t3.cid ; 

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 distinct t1.sid,t1.sname,t2.cid, t2.grade FROM t_student t1, t_score t2    WHERE t2.grade >=70 AND t2.sid = t1.sid; 

37、查询不及格的课程，并按课程号从大到小排列 

select cid from  t_score where grade < 60 order by cid ; 

38、查询课程编号为3且课程成绩在80分以上的学生的学号和姓名； 

select t1.sid,t2.sname from t_score t1,t_student t2where t1.sid = t2.sid and t1.grade > 80 and t1.cid = '3'; 

40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩 

select t1.sname,t2.grade from t_student t1, t_score t2,t_course t3,t_teacher t4where t1.sid = t2.sid and  t2.cid = t3.cid and  t3.tid = t4.tid and  t4.Tname = '叶平' and  t2.grade = (select max(grade )from t_score where cid=t3.cid ); 

42、查询不同课程成绩相同的学生的学号、课程号、学生成绩 

select distinct t1.sid,t2.grade  from  t_score t1 , t_score t2 where t1.grade = t2.grade  and t1.cid <>t2.cid ; 

44、统计每门课程的学生选修人数（超过10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，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 as 课程号,count(*) as 人数 from  t_scoregroup by cid     order by count(*) desc,cid 

45、检索至少选修两门课程的学生学号 

select sid from t_score group by sid having count(*) >= 2 

46、查询全部学生都选修的课程的课程号和课程名 

select cid,cname from t_course where cid in (select cid from  t_score group by cid)

47、查询没学过“叶平”老师讲授的任一门课程的学生姓名 

select sname from t_student where sid not in (select sid from t_course t1,t_teacher t2, t_score t3where t1.tid = t2.tid and   t3.cid =t1.cid and   t2.tname = '叶平'); 

48、查询两门以上不及格课程的同学的学号及其平均成绩 

select sid,avg(ifnull(grade ,0)) from t_score where sid in (select sid from t_score where grade <60 group by sid having count(*)>2)group by sid; 

49、检索“4”课程分数小于60，按分数降序排列的同学学号 

select sid from  t_score where cid='4'and grade <60 order by grade  desc;