企业SQL笔试_quertions（48道面试题）

Student(SID, Sname, Sage, Ssex) 学生表
Course(CID, Cname, TID) 课程表
SC(SID, CID, score) 成绩表
Teacher(TID, Tname) 教师表

问题：
1、查询“001”课程比“002”课程成绩高的所有学生的学号；

SELECT * FROM SC SC1,SC SC2
       WHERE SC1.CID='01' AND SC2.CID='02' AND SC1.SID=SC2.SID AND SC1.SCORE > SC2.SCORE;

2、查询平均成绩大于60分的同学的学号和平均成绩；

  SELECT SC.SID,ROUND(AVG(NVL(SC.SCORE,0)),1) AVGSCORE FROM SC GROUP BY SC.SID HAVING AVG(NVL(SC.SCORE,0)) >= 60;

3、查询所有同学的学号、姓名、选课数、总成绩；

SELECT S.SID,S.SNAME,COUNT(SC.CID) SOURCE_COUNT,SUM(SC.SCORE) SUM_SCORE FROM STUDENT S
       LEFT JOIN SC ON S.SID=SC.SID
       GROUP BY S.SID,S.SNAME;

4、查询姓“李”的老师的个数；

SELECT COUNT(1) FROM TEACHER T WHERE T.TNAME LIKE '李%'

5、查询没学过“叶平”老师课的同学的学号、姓名；

 SELECT *FROM STUDENT WHERE SID NOT IN(
  SELECT S.SID FROM STUDENT S
       LEFT JOIN SC ON S.SID=SC.SID
       LEFT JOIN COURSE C ON SC.CID = C.CID
       LEFT JOIN TEACHER T ON T.TID=C.TID
       WHERE T.TNAME='叶平'
)

6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

SELECT * FROM STUDENT S, SC C1, SC C2 WHERE C1.CID='01' AND C2.CID='02'
       AND S.SID = C1.SID AND S.SID = C2.SID

7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；

SELECT STU_COURSE.SID,STU_COURSE.SNAME,COUNT(STU_COURSE.CID) FROM  
       (SELECT S.SID,S.SNAME,SC.CID FROM STUDENT S LEFT JOIN SC ON S.SID = SC.SID WHERE SC.CID IN
               (SELECT C.CID FROM COURSE C, TEACHER T WHERE C.TID=T.TID AND T.TNAME='叶平')) STU_COURSE
       GROUP BY STU_COURSE.SID,STU_COURSE.SNAME HAVING COUNT(STU_COURSE.CID)=
             (SELECT COUNT(C.CID) FROM COURSE C,TEACHER T WHERE C.TID=T.TID AND T.TNAME='叶平')

8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；

SELECT S.SID,S.SNAME FROM SC SC1 , SC SC2,STUDENT S
WHERE SC1.SID = SC2.SID 
AND SC1.CID = '001' 
AND SC2.CID = '002' 
AND SC1.SCORE < SC2.SCORE

9、查询所有课程成绩小于60分的同学的学号、姓名；

SELECT DISTINCT SC1.SID,S.SNAME FROM SC SC1, STUDENT S WHERE S.SID NOT IN            
(SELECT DISTINCT SC.SID FROM SC WHERE SC.SCORE >= 60) AND SC1.SID=S.SID

10、查询没有学全所有课的同学的学号、姓名；

   SELECT S.SID,S.SNAME,COUNT(SC.CID) COURSE_COUNT
       FROM STUDENT S LEFT JOIN SC ON S.SID=SC.SID GROUP BY S.SID,S.SNAME
       HAVING COUNT(SC.CID)<(SELECT COUNT(1) FROM COURSE)

11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；

 SELECT DISTINCT S.* FROM STUDENT S LEFT JOIN SC C ON S.SID=C.SID 
       WHERE C.CID IN 
       (SELECT SC.CID FROM SC WHERE SC.SID='01') AND S.SID <> '01'

12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；

 SELECT S.SID,S.SNAME FROM STUDENT S
  WHERE S.SID IN
  (SELECT DISTINCT S.SID FROM SC WHERE SC.CID NOT IN (SELECT SC.CID FROM SC WHERE S.SID='01'))

13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；

 update sc sc3 
       set sc3.score = (select round(avg(sc.score),2) avgscore from teacher t ,course c, sc where t.tid = c.cid and c.cid = sc.cid and t.tname = '叶平'
       and c.cid = sc3.cid group by c.cid) 
       where sc3.cid in 
       (select c.cid from teacher t,course c,sc where t.tid=c.cid and c.cid=sc.cid and t.tname = '叶平'
       group by c.cid)

14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；

    select * from student s,(select sc4.sid,count(1) course_count from sc sc4 group by sc4.sid) a,
(select sc2.sid,count(sc2.cid) course_count from sc sc2 where sc2.cid in(
       select * from sc sc1 where sc1.sid = '1002'
       )group by sc2.sid having count(sc2.cid) < (select count(1) from sc sc3 where sc3.sid = '1002')) b
       where a.sid = b.sid and a.course_count = b.course_count and s.sid = a.sid and s.sid <> '1002'
	

---

15、删除学习“叶平”老师课的SC表记录；

  delete from sc
       where sc.cid in
       (select c.cid from teacher t,course c where t.tid = c.tid and t.tname = '叶平')

16、向SC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“003”课程的同学学号、2号课的平均成绩；

 SELECT '03',A.SID,B.AVGSCORE FROM(
       SELECT * FROM STUDENT S WHERE S.SID NOT IN (SELECT SC.SID FROM SC WHERE SC.CID='03')) A LEFT JOIN(
       SELECT ROUND(AVG(SC.SCORE),2) AVGSCORE FROM SC WHERE SC.CID = '02') B ON 1=1 

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 '03',A.SID,B.AVGSCORE FROM(
       SELECT * FROM STUDENT S WHERE S.SID NOT IN (SELECT SC.SID FROM SC WHERE SC.CID='03')) A LEFT JOIN(
       SELECT ROUND(AVG(SC.SCORE),2) AVGSCORE FROM SC WHERE SC.CID = '02') B ON 1=1 

18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分

  SELECT SC.CID,MIN(SC.SCORE) MINSCORE,MAX(SC.SCORE) MAXSCORE FROM SC 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

SELECT SC.CID,ROUND(AVG(SC.SCORE),2) AVGSCORE,
   ROUND((SELECT COUNT(SC1.CID) FROM SC SC1 WHERE SC1.CID = SC.CID AND SC1.SCORE>=60)/COUNT(SC.SID),2) JIGELV
   
       FROM SC GROUP BY SC.CID ORDER BY AVGSCORE,JIGELV DESC

20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）

 SELECT MAX(DECODE(V1.CID,'01',V1.CID || ' - ' || V1.AVGSCORE || ' - ' || V1.JIGELV)) "语文",
       MAX(DECODE(V1.CID,'01',V1.CID || ' - ' || V1.AVGSCORE || ' - ' || V1.JIGELV)) "数学"
       from v1

21、查询不同老师所教不同课程平均分从高到低显示

SELECT T.TID, C.CID, AVG(SC.SCORE) AVGSCORE FROM SC, COURSE C,TEACHER T
       WHERE SC.CID = C.CID AND C.TID = T.TID
       GROUP BY T.TID,C.CID ORDER BY AVGSCORE DESC

22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004）

    SELECT * FROM( 
SELECT * FROM (
       SELECT SC.CID,SC.SCORE "语文",ROWNUM R FROM SC WHERE SC.CID='01' AND ROWNUM<=6 ORDER BY SC.SCORE DESC) A
       WHERE A.R>=3  ORDER BY A.R) SCORE1
UNION ALL     
SELECT * FROM(       
SELECT * FROM (
       SELECT SC.CID,SC.SCORE "数学",ROWNUM R FROM SC WHERE SC.CID='02' AND ROWNUM<=6 ORDER BY SC.SCORE DESC) A
       WHERE A.R>=3  ORDER BY A.R) SCORE2

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 C.CID,C.CNAME, COUNT(S.SID),
       (SELECT COUNT(SC.SID) FROM SC WHERE SC.CID = C.CID AND SC.SCORE > 85) "85-100人数",
       (SELECT COUNT(SC.SID) FROM SC WHERE SC.CID = C.CID AND SC.SCORE >= 60 AND SC.SCORE <= 85) "60-85人数"
       FROM SC S,COURSE C WHERE S.CID = C.CID GROUP BY C.CID,C.CNAME

24、查询学生平均成绩及其名次

  SELECT A.*, 
       (    SELECT COUNT(1)
            FROM (SELECT SC.SID,AVG(SC.SCORE) AVGSCORE FROM SC GROUP BY SC.SID)B WHERE B.AVGSCORE>A.AVGSCORE)+1 MC
       FROM(
       SELECT SC.SID,AVG(SC.SCORE) AVGSCORE FROM SC GROUP BY SC.SID) A ORDER BY MC

25、查询各科成绩前三名的记录:(不考虑成绩并列情况)

select a.sid,a.cid,a.score from sc a
left join sc b
on a.cid = b.cid and a.score group by a.cid, a.sid,a.score
having count(b.cid)❤️
order by a.cid;

26、查询每门课程被选修的学生数

select sc.cid,count(s.sid) "人数" from sc,student s
       group by sc.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 sc.sid,s.sname,count(sc.cid) "选课数" 
       from sc, student s 
       where sc.sid = s.sid group by sc.sid,
       s.sname having count(sc.cid)=1

28、查询男生、女生人数

 SELECT COUNT(SSEX) AS 男生人数 FROM STUDENT S 
       GROUP BY SSEX HAVING SSEX='男';
        
SELECT COUNT(SSEX) AS 女生人数 FROM STUDENT S 
       GROUP BY SSEX HAVING SSEX='女';   

29、查询姓“张”的学生名单

  SELECT * FROM STUDENT S WHERE S.SNAME LIKE '张%' 

30、查询同名同性学生名单，并统计同名人数

SELECT S.SNAME,COUNT(*) FROM STUDENT S GROUP BY S.SNAME HAVING COUNT(*)>1

31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)

 select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age
       from student
       where CONVERT(char(11),DATEPART(year,Sage))='1981';

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 sc.cid,avg(sc.score) "mean" from sc
       group by sc.cid
       order by avg(sc.score) asc,sc.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 s.sname,sc.sid,avg(sc.score) from student s, sc
       where s.sid = sc.sid group by sc.sid,s.sname having avg(sc.score)>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 s.sname,sc.score from student s, sc
       where s.sid = sc.sid group by sc.sid,sc.score,s.sname having sc.score < 60

35、查询所有学生的选课情况；

 select sc.sid,sc.cid,s.sname,c.cname 
       from sc,student s,course c
       where sc.sid = s.sid and sc.cid=c.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 s.sid,s.sname,sc.cid,sc.score
       from student s,sc
       where sc.score >=70 and sc.sid = s.sid

37、查询不及格的课程，并按课程号从大到小排列

 select * from sc where sc.score<60 order by sc.cid 

38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；

  select s.sid,s.sname from sc,student s where sc.score>80 
       and sc.cid='003'
       and sc.sid = s.sid

39、求选了课程的学生人数

select count(*) from sc

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 s.sname,sc.score
from student s,sc,course c,teacher t
where s.sid=sc.sid and sc.cid = c.cid
and c.tid = t.tid and t.tname = ‘叶平’ and sc.score = (select max(score)from sc where sc.cid = c.cid)
and rownum<=1;

41、查询各个课程及相应的选修人数

 select count(*) from sc group by sc.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 a.sid,b.score from sc a,sc b where a.score = b.score and a.cid <> b.cid

43、查询每门功成绩最好的前两名

select a.sid,a.cid,a.score from sc a
left join sc b
on a.cid = b.cid and a.score group by a.cid, a.sid,a.score
having count(b.cid)<2
order by a.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 sc.cid, COUNT( distinct sc.sid) as num FROM sc
GROUP BY sc.cid HAVING count(sc.sid)>10 
ORDER BY num DESC,sc.cid ASC

45、检索至少选修两门课程的学生学号

select sc.sid from sc
group by sc.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 * from course c where c.cid in(
select sc.cid from sc group by sc.cid having count(sc.sid)=(select count(1) from student) )

47、查询没学过“叶平”老师讲授的任一门课程的学生姓名

select * from student where sid not in (
select s.sid from student s
left join sc on s.sid = sc.sid
left join course c on sc.cid = c.cid
left join teacher t on c.tid = t.tid
where t.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 c1.sid,avg(c1.score) from sc c1 where c1.sid in(
       select sc.sid 
       from sc where sc.score < 60 
       group by sc.sid 
       having count(sc.cid) >= 2) 
       group by c1.sid