create table Student(SId varchar(10),Sname varchar(10),Sage date,Ssex varchar(10));
insert into Student values(‘01‘ , ‘赵雷‘ , to_date(‘1990-01-01‘,‘yyyy-mm-dd‘), ‘男‘);
insert into Student values(‘02‘ , ‘钱电‘ , to_date(‘1990-12-21‘,‘yyyy-mm-dd‘) , ‘男‘);
insert into Student values(‘03‘ , ‘孙风‘ , to_date(‘1990-12-20‘,‘yyyy-mm-dd‘) , ‘男‘);
insert into Student values(‘04‘ , ‘李云‘ , to_date(‘1990-12-06‘,‘yyyy-mm-dd‘) , ‘男‘);
insert into Student values(‘05‘ , ‘周梅‘ , to_date(‘1991-12-01‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘06‘ , ‘吴兰‘ , to_date(‘1992-01-01‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘07‘ , ‘郑竹‘ , to_date(‘1989-01-01‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘09‘ , ‘张三‘ , to_date(‘2017-12-20‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘10‘ , ‘李四‘ , to_date(‘2017-12-25‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘11‘ , ‘李四‘ , to_date(‘2012-06-06‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘12‘ , ‘赵六‘ , to_date(‘2013-06-13‘,‘yyyy-mm-dd‘) , ‘女‘);
insert into Student values(‘13‘ , ‘孙七‘ , to_date(‘2014-06-01‘,‘yyyy-mm-dd‘) , ‘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);

----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.SID SID,ST.SNAME NAME,S1.SCORE SCORE1,S2.SCORE SCORE2
FROM (SELECT * FROM SC WHERE CID = ‘01‘) S1,
     (SELECT * FROM SC WHERE CID = ‘02‘) S2,
     STUDENT ST
WHERE S1.SID = S2.SID
AND   S1.SCORE > S2.SCORE
AND   S1.SID = ST.SID;


---1.1 查询同时存在" 01 "课程和" 02 "课程的情况
SELECT ST.SID SID,ST.SNAME NAME,S1.SCORE SCORE1,S2.SCORE SCORE2
FROM (SELECT * FROM SC WHERE CID = ‘01‘) S1,
     (SELECT * FROM SC WHERE CID = ‘02‘) S2,
     STUDENT ST
WHERE S1.SID = S2.SID
AND   S1.SID = ST.SID;

----1.2 查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 NULL )
SELECT *
FROM (SELECT * FROM SC WHERE SC.CID = ‘01‘) SC1 
LEFT JOIN
(SELECT * FROM SC WHERE SC.CID = ‘02‘) SC2    
ON SC1.SID = SC2.SID;


----1.3 查询不存在" 01 "课程但存在" 02 "课程的情况
SELECT *
FROM SC
WHERE SC.SID NOT IN
      (SELECT SID FROM SC WHERE SC.CID = ‘01‘) 
AND SC.CID = ‘02‘;

----2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 * FROM (SELECT SC.SID SSID,ST.SNAME NAME,AVG(SC.SCORE) AV
FROM STUDENT ST,SC
WHERE ST.SID = SC.SID
GROUP BY SC.SID ,ST.SNAME
) RS
WHERE RS.AV >= 60
ORDER BY RS.AV;
---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(没成绩的显示为 NULL )
SELECT ST.SID,ST.SNAME,SCC.CIDS,SCC.SCORES
FROM STUDENT ST LEFT JOIN
(SELECT SC.SID SSID,ST.SNAME NAME,COUNT(SC.CID) CIDS,SUM(SC.SCORE) SCORES
     FROM STUDENT ST,SC
     WHERE ST.SID = SC.SID
     GROUP BY SC.SID ,ST.SNAME) SCC
ON ST.SID = SCC.SSID;
-- 查有成绩的学生信息
SELECT SC.SID SSID,ST.SNAME NAME,COUNT(SC.CID) CIDS,SUM(SC.SCORE) SUM
FROM STUDENT ST,SC
WHERE ST.SID = SC.SID
GROUP BY SC.SID ,ST.SNAME;
--查询「李」姓老师的数量
SELECT COUNT(*) FROM TEACHER TR WHERE TR.TNAME LIKE ‘李%‘ ;
--查询学过「张三」老师授课的同学的信息
SELECT ST.SID,ST.SNAME
FROM TEACHER TR,SC,STUDENT ST,COURSE CS
WHERE TR.TNAME = ‘张三‘
AND TR.TID = CS.TID
AND CS.CID = SC.CID
AND ST.SID = SC.SID;
--查询没有学全所有课程的同学的信息
SELECT ST.SID,ST.SNAME FROM STUDENT ST
WHERE ST.SID NOT IN(
SELECT SID FROM(
  SELECT SID,COUNT(CID) CIDS
  FROM SC
  GROUP BY SID) NL
WHERE NL.CIDS = (SELECT COUNT(CID) FROM COURSE));
--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 * FROM STUDENT WHERE SID IN(
SELECT DISTINCT SID FROM SC WHERE CID IN(
SELECT SC.CID FROM SC WHERE SC.SID = ‘01‘));
--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
WITH B AS (SELECT DISTINCT CID AS DISTINCT_CID FROM SC WHERE SID = ‘01‘)
SELECT * FROM STUDENT
WHERE SID IN
(
  SELECT SC.SID FROM SC LEFT JOIN B
  ON B.DISTINCT_CID = SC.CID
  GROUP BY SC.SID
  HAVING COUNT(SC.CID) = (SELECT COUNT(DISTINCT_CID) FROM B )
  AND COUNT(B.DISTINCT_CID) = (SELECT COUNT(DISTINCT_CID) FROM B )
);
--查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT ST.SNAME,ST.SID FROM STUDENT ST
WHERE ST.SID NOT IN (SELECT SC.SID SSID FROM TEACHER TR,COURSE CS,SC
WHERE TR.TNAME = ‘张三‘
AND TR.TID = CS.TID
AND CS.CID = SC.CID);

--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
WITH B AS (SELECT DISTINCT SID,COUNT(SID) NUMS FROM SC WHERE SC.SCORE < 60 GROUP BY SID)
SELECT ST.* FROM STUDENT ST RIGHT JOIN B
ON ST.SID = B.SID
AND B.NUMS >1;
--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.SCORE FROM SC,STUDENT ST 
WHERE SC.CID = ‘01‘ 
AND SC.SCORE < 60
AND ST.SID = SC.SID
ORDER BY SCORE DESC;
--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
WITH B AS (SELECT DISTINCT SID DISTINCT_SID,AVG(SCORE) AVGSCORE FROM SC GROUP BY SID)
SELECT SID,CID, SCORE,B.AVGSCORE 
FROM SC LEFT JOIN B
ON B.DISTINCT_SID = SC.SID
ORDER BY B.AVGSCORE DESC,CID ASC,SID ASC;
--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
SELECT DISTINCT SC.CID DISTINCT_CID,CS.CNAME,COUNT(CS.CID) NUMS,MAX(SCORE) MAX_SCORE,MIN(SCORE) MIN_SCORE,ROUND(AVG(SCORE),2) AVG_SCORE，
ROUND(100*SUM(CASE WHEN SC.SCORE>=60 THEN 1 ELSE 0 END)/COUNT(CS.CID),2)||‘%‘ AS 及格率,
ROUND(100*SUM(CASE WHEN SC.SCORE>=70 AND SC.SCORE <80 THEN 1 ELSE 0 END)/COUNT(CS.CID),2)||‘%‘ AS 中等率,
ROUND(100*SUM(CASE WHEN SC.SCORE>=80 AND SC.SCORE <90 THEN 1 ELSE 0 END)/COUNT(CS.CID),2)||‘%‘ AS 优良率,
ROUND(100*SUM(CASE WHEN SC.SCORE>=90 THEN 1 ELSE 0 END)/COUNT(CS.CID),2)||‘%‘ AS 优秀率
FROM SC,COURSE CS
WHERE SC.CID = CS.CID 
GROUP BY SC.CID,CS.CNAME
ORDER BY NUMS DESC,DISTINCT_CID ASC;
--按各科成绩进行排序，并显示排名， SCORE 重复时保留名次空缺
SELECT CID,SID,SCORE, RANK() OVER(PARTITION BY CID  ORDER BY SCORE DESC) RANK
FROM SC
GROUP BY CID,SID,SCORE
ORDER BY CID,SCORE DESC,RANK;
--按各科成绩进行排序，并显示排名， SCORE 重复时合并名次
SELECT CID,SID,SCORE, ROW_NUMBER() OVER(PARTITION BY CID  ORDER BY SCORE DESC) RANK
FROM SC
GROUP BY CID,SID,SCORE
ORDER BY CID,SCORE DESC,RANK;
--查询学生的总成绩，并进行排名，总分重复时保留名次空缺
SELECT DISTINCT A.SID ID,SUM(A.SCORE) ZF,ROW_NUMBER() OVER(ORDER BY SUM(A.SCORE) DESC) RANK
  FROM SC A 
  GROUP BY SID
  ORDER BY SUM(SCORE) DESC;
--查询学生的总成绩，并进行排名，总分重复时不保留名次空缺
SELECT DISTINCT A.SID ID,SUM(A.SCORE) ZF,RANK() OVER(ORDER BY SUM(A.SCORE) DESC) RANK
  FROM SC A 
  GROUP BY SID
  ORDER BY SUM(SCORE) DESC;
    
--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]，[60-0] 及所占百分比
SELECT SC.CID,CS.CNAME,
SUM((CASE WHEN SC.SCORE>=85 THEN 1 ELSE 0 END)) QJ1,
ROUND(SUM((CASE WHEN SC.SCORE>=85 THEN 1 ELSE 0 END))/SUM(SC.SCORE)*100,2)||‘%‘ QJ1L,  
SUM((CASE WHEN SC.SCORE<85 AND SC.SCORE >=70 THEN 1 ELSE 0 END)) QJ2, 
ROUND(SUM((CASE WHEN SC.SCORE<85 AND SC.SCORE >=70 THEN 1 ELSE 0 END))/SUM(SC.SCORE)*100,2)||‘%‘ QJ2L, 
SUM((CASE WHEN SC.SCORE<70 AND SC.SCORE >=60 THEN 1 ELSE 0 END)) QJ3, 
ROUND(SUM((CASE WHEN SC.SCORE<70 AND SC.SCORE >=60 THEN 1 ELSE 0 END))/SUM(SC.SCORE)*100,2)||‘%‘ QJ3L, 
SUM((CASE WHEN SC.SCORE<60 THEN 1 ELSE 0 END)) QJ4,
ROUND(SUM((CASE WHEN SC.SCORE<60 THEN 1 ELSE 0 END))/SUM(SC.SCORE)*100,2)||‘%‘ QJ4L
FROM COURSE CS,SC
WHERE SC.CID = CS.CID
GROUP BY SC.CID,CS.CNAME;
--查询各科成绩前三名的记录
SELECT *
FROM (SELECT CID,SID,SCORE, RANK() OVER(PARTITION BY CID  ORDER BY SCORE DESC) RANK
    FROM SC
    GROUP BY CID,SID,SCORE
    ORDER BY CID,SCORE DESC,RANK) B
WHERE B.RANK <=3;
--查询每门课程被选修的学生数
SELECT SC.CID,CS.CNAME,COUNT(SC.SID)
FROM SC,COURSE CS
WHERE SC.CID = CS.CID
GROUP BY SC.CID,CS.CNAME;
--查询出只选修两门课程的学生学号和姓名
SELECT * FROM (
SELECT SC.SID,ST.SNAME,COUNT(SC.SID) NUMS
FROM SC,STUDENT ST
WHERE ST.SID = SC.SID
GROUP BY SC.SID,ST.SNAME) B
WHERE B.NUMS=2;
--查询男生、女生人数
SELECT SSEX,SUM(SID) 
FROM STUDENT ST
GROUP BY SSEX;
--查询名字中含有「风」字的学生信息
SELECT * FROM STUDENT WHERE SNAME LIKE ‘%风%‘;
--查询同名同性学生名单，并统计同名人数
SELECT T1.SSEX,T1.SNAME,COUNT(T1.SID)
FROM STUDENT T1,STUDENT T2
WHERE T1.SNAME = T2.SNAME
AND T1.SSEX = T2.SSEX
AND T1.SID != T2.SID
GROUP BY T1.SSEX,T1.SNAME;
--查询 1990 年出生的学生名单
SELECT * FROM STUDENT WHERE TO_CHAR(SAGE,‘YYYY/MM/DD‘) LIKE ‘1990%‘;
--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 SID,AVG(SCORE) AVERAGE FROM SC GROUP BY SID ORDER BY AVERAGE DESC,SID;
--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.SID,ST.SNAME,T.AVERAGE
FROM STUDENT ST ,(
SELECT SID,AVG(SCORE) AVERAGE FROM SC GROUP BY SID) T
WHERE T.AVERAGE >=85
AND T.SID = ST.SID;
--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.SID,ST.SNAME,SC.CID,SC.SCORE
FROM COURSE CS,STUDENT ST,SC
WHERE CS.CNAME = ‘数学‘
AND ST.SID = SC.SID
AND SC.CID = CS.CID
AND SC.SCORE < 60;
--查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）
SELECT ST.SID,SC.CID,SC.SCORE
FROM SC RIGHT JOIN STUDENT ST
ON ST.SID = SC.SID;
--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 SC.SID,CS.CNAME,SC.SCORE
FROM SC,COURSE CS,(SELECT SID,MIN(SCORE) MIN_SCORE FROM SC GROUP BY SID) A
WHERE SC.SID =A.SID
AND SC.CID = CS.CID
AND A.MIN_SCORE >=70
ORDER BY SC.SID;
--查询不及格的课程
SELECT SC.SID,SC.CID,CS.CNAME,SC.SCORE
FROM COURSE CS , SC
WHERE SC.CID = CS.CID
AND SC.SCORE < 60;

--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.SID,ST.SNAME,SC.CID,SC.SCORE
FROM STUDENT ST,SC
WHERE SC.CID = ‘01‘ 
AND ST.SID = SC.SID
AND SC.SCORE >= 80;

--求每门课程的学生人数
SELECT SC.CID,COUNT(SC.CID)
FROM COURSE CS LEFT JOIN SC
ON CS.CID = SC.CID
GROUP BY SC.CID;
--成绩不重复，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.SCORE
FROM TEACHER TR,STUDENT ST,COURSE CS,SC
WHERE SC.CID=CS.CID
AND TR.TID = CS.TID
AND ST.SID = SC.SID
AND TR.TNAME = ‘张三‘
AND ROWNUM = 1
ORDER BY SC.SCORE DESC;
--成绩有重复的情况下，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 * FROM
(SELECT T.SSID,T.NAME,T.SR, RANK() OVER(ORDER BY T.SR DESC) RANK
FROM
(SELECT ST.SID SSID,ST.SNAME NAME,SC.SCORE SR
FROM TEACHER TR,STUDENT ST,COURSE CS,SC
WHERE SC.CID=CS.CID
AND TR.TID = CS.TID
AND ST.SID = SC.SID
AND TR.TNAME = ‘张三‘) T)
WHERE RANK = 1;
--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 SC1.SID,SC1.CID,SC1.SCORE
FROM SC SC1 , SC SC2
WHERE SC1.SCORE = SC2.SCORE
AND SC1.SID = SC2.SID
AND SC1.CID != SC2.CID;
--查询每门功成绩最好的前两名
SELECT *
FROM(SELECT SC.CID,SC.SID,SC.SCORE,RANK() OVER(PARTITION BY SC.CID ORDER BY SC.SCORE DESC) RANK FROM SC ) T
WHERE T.RANK <=2;
--统计每门课程的学生选修人数（超过 5 人的课程才统计）。
SELECT * FROM
(SELECT SC.CID,COUNT(SC.SID) NUMS FROM SC GROUP BY SC.CID) T
WHERE T.NUMS>=5;
--检索至少选修两门课程的学生学号
SELECT * FROM
(SELECT SC.SID,COUNT(SC.CID) NUMS FROM SC GROUP BY SC.SID) T
WHERE T.NUMS >=2;
--查询选修了全部课程的学生信息
SELECT ST.* FROM
(SELECT SC.SID SSID,COUNT(SC.CID) NUMS FROM SC GROUP BY SC.SID) T,
STUDENT ST
WHERE T.NUMS = (SELECT COUNT(CID) FROM COURSE)
AND ST.SID = T.SSID;
--查询各学生的年龄，只按年份来算
SELECT ST.*,(SELECT EXTRACT(YEAR FROM SYSDATE) FROM DUAL)-SUBSTR(TO_CHAR(ST.SAGE,‘YYYY/MM/DD‘),0,4) AGE
FROM STUDENT ST;
--按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
SELECT ST.*,
(SELECT EXTRACT(YEAR FROM SYSDATE) FROM DUAL)-SUBSTR(TO_CHAR(ST.SAGE,‘YYYY/MM/DD‘),0,4)
-(CASE WHEN TO_CHAR(SYSDATE,‘MMDD‘) > TO_CHAR(ST.SAGE,‘MMDD‘) THEN 1 ELSE 0 END ) AGE
FROM STUDENT ST;
--查询本周过生日的学生
WITH T AS (SELECT TO_CHAR(TRUNC(NEXT_DAY(SYSDATE-8,1)+1)+ROWNUM-1,‘YYYYMMDD‘) DAYS
FROM DUAL
CONNECT BY ROWNUM<=TRUNC(TRUNC(NEXT_DAY(SYSDATE-8,1)+7)+1-TRUNC(NEXT_DAY(SYSDATE-8,1)+1)))
SELECT ST.* FROM STUDENT ST
WHERE TO_CHAR(ST.SAGE,‘MMDD‘) IN (SELECT SUBSTR(T.DAYS,5,4) FROM T);
--查询下周过生日的学生
WITH T AS (SELECT TO_CHAR(TRUNC(NEXT_DAY(SYSDATE-8,1)+8)+ROWNUM-1,‘YYYYMMDD‘) DAYS
FROM DUAL
CONNECT BY ROWNUM<=TRUNC(TRUNC(NEXT_DAY(SYSDATE-8,1)+14)+1-TRUNC(NEXT_DAY(SYSDATE-8,1)+8)))
SELECT ST.* FROM STUDENT ST
WHERE TO_CHAR(ST.SAGE,‘MMDD‘) IN (SELECT SUBSTR(T.DAYS,5,4) FROM T);
--查询本月过生日的学生
SELECT ST.* FROM STUDENT ST
WHERE SUBSTR(TO_CHAR(ST.SAGE,‘YYYYMMDD‘),5,2) = SUBSTR(TO_CHAR(SYSDATE,‘YYYYMMDD‘),5,2);
--查询下月过生日的学生
SELECT ST.* FROM STUDENT ST
WHERE SUBSTR(TO_CHAR(ST.SAGE,‘YYYYMMDD‘),5,2) = SUBSTR(TO_CHAR(ADD_MONTHS(SYSDATE,1),‘YYYYMMDD‘),5,2);