Mysql面试题及答案大全

表
– Student(sid,Sname,Sage,Ssex) 学生表
CREATE TABLE student (
sid VARCHAR(10) NOT NULL,
sName VARCHAR(20) DEFAULT NULL,
sAge DATETIME DEFAULT ‘1980-10-12 23:12:36’,
sSex VARCHAR(10) DEFAULT NULL,
PRIMARY KEY (sid)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

– Course(cid,Cname,tid) 课程表
CREATE TABLE course (
cid VARCHAR(10) NOT NULL,
cName VARCHAR(10) DEFAULT NULL,
tid INT(20) DEFAULT NULL,
PRIMARY KEY (cid)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

– SC(sid,cid,score) 成绩表
CREATE TABLE sc (
sid VARCHAR(10) DEFAULT NULL,
cid VARCHAR(10) DEFAULT NULL,
score INT(10) DEFAULT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8;

– Teacher(tid,Tname) 教师表
CREATE TABLE teacher (
tid INT(10) DEFAULT NULL,
tName VARCHAR(10) DEFAULT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8;
数据
INSERT INTO course(cid,cName,tid) VALUES (‘001’,‘企业管理’,3);
INSERT INTO course(cid,cName,tid) VALUES (‘002’,‘马克思’,3);
INSERT INTO course(cid,cName,tid) VALUES (‘004’,‘数据库’,1);
INSERT INTO course(cid,cName,tid) VALUES (‘005’,‘英语’,1);

INSERT INTO sc(sid,cid,score) VALUES (‘1001’,‘001’,80);
INSERT INTO sc(sid,cid,score) VALUES (‘1001’,‘002’,60);
INSERT INTO sc(sid,cid,score) VALUES (‘1001’,‘003’,70);
INSERT INTO sc(sid,cid,score) VALUES (‘1002’,‘001’,85);
INSERT INTO sc(sid,cid,score) VALUES (‘1002’,‘002’,70);
INSERT INTO sc(sid,cid,score) VALUES (‘1003’,‘004’,90);
INSERT INTO sc(sid,cid,score) VALUES (‘1003’,‘001’,90);
INSERT INTO sc(sid,cid,score) VALUES (‘1003’,‘002’,99);
INSERT INTO sc(sid,cid,score) VALUES (‘1004’,‘002’,65);
INSERT INTO sc(sid,cid,score) VALUES (‘1004’,‘003’,50);
INSERT INTO sc(sid,cid,score) VALUES (‘1005’,‘005’,80);
INSERT INTO sc(sid,cid,score) VALUES (‘1005’,‘004’,70);
INSERT INTO sc(sid,cid,score) VALUES (‘1003’,‘003’,10);
INSERT INTO sc(sid,cid,score) VALUES (‘1003’,‘005’,10);

INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1001’,‘张三丰’,(‘1980-10-12 23:12:36’),‘男’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1002’,‘张无极’,(‘1995-10-12 23:12:36’),‘男’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1003’,‘李奎’,(‘1992-10-12 23:12:36’),‘女’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1004’,‘李元宝’,(‘1980-10-12 23:12:36’),‘女’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1005’,‘李世明’,(‘1981-10-12 23:12:36’),‘男’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1006’,‘赵六’,(‘1986-10-12 23:12:36’),‘男’);
INSERT INTO student(sid,sName,sAge,sSex) VALUES (‘1007’,‘田七’,(‘1981-10-12 23:12:36’),‘女’);

INSERT INTO teacher(tid,tName) VALUES (1,‘李老师’);
INSERT INTO teacher(tid,tName) VALUES (2,‘何以琛’);
INSERT INTO teacher(tid,tName) VALUES (3,‘叶平’);

问题与答案

1.查询“001”课程比“002”课程成绩高的所有学生的学号;
SELECT a.sid FROM (SELECT sid,score FROM SC WHERE cid=‘001’) a,(SELECT sid,score
FROM SC WHERE cid=‘002’) b
WHERE a.score>b.score AND a.sid=b.sid;

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,Student.Sname,COUNT(SC.cid),SUM(score)
FROM Student LEFT OUTER JOIN SC ON Student.sid=SC.sid
GROUP BY Student.sid,Sname
4、查询姓“李”的老师的个数;
SELECT COUNT(DISTINCT(Tname))
FROM 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 Student.sid,Student.Sname
FROM Student
WHERE sid NOT IN (SELECT DISTINCT( SC.sid) FROM SC,Course,Teacher WHERE SC.cid=Course.cid AND Teacher.tid=Course.tid AND Teacher.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;
A:SELECT Student.sid,Student.Sname FROM Student,SC WHERE Student.sid=SC.sid AND SC.cid='001’AND EXISTS( SELECT * FROM SC AS SC_2 WHERE SC_2.sid=SC.sid AND SC_2.cid=‘002’);
B:SELECT s.sid,s.sName
FROM student s, (SELECT sid,COUNT(cid) FROM sc WHERE cid IN (‘001’,‘002’) GROUP BY sid HAVING COUNT(cid)>=2) t WHERE s.sid = t.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 sid,Sname
FROM Student
WHERE sid IN (SELECT sid FROM SC ,Course ,Teacher WHERE SC.cid=Course.cid AND Teacher.tid=Course.tid AND Teacher.Tname=‘叶平’ GROUP BY sid HAVING COUNT(SC.cid)=(SELECT COUNT(cid) FROM Course,Teacher WHERE Teacher.tid=Course.tid AND 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;
1>SELECT sid,Sname FROM (SELECT Student.sid,Student.Sname,score ,(SELECT score FROM SC SC_2 WHERE SC_2.sid=Student.sid AND SC_2.cid=‘002’) score2
FROM Student,SC WHERE Student.sid=SC.sid AND cid=‘001’) S_2 WHERE score2 2>SELECT s.sid,s.sName FROM student s,
(SELECT sid,score FROM sc WHERE cid = ‘001’) sc_1,
(SELECT sid,score FROM sc WHERE cid = ‘002’) sc_2
WHERE sc_1.sid = sc_2.sid AND s.sid = sc_2.sid AND sc_2.score < sc_1.score
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 Student
WHERE sid NOT IN (SELECT Student.sid FROM Student,SC WHERE S.sid=SC.sid AND score>60);
10、查询没有学全所有课的同学的学号、姓名;
1>
SELECT Student.sid,Student.Sname
FROM Student,SC
WHERE Student.sid=SC.sid GROUP BY Student.sid,Student.Sname HAVING COUNT(cid) <(SELECT COUNT(cid) FROM Course);
2>
SELECT s.sid,s.sname FROM student s,
(SELECT sid,COUNT(cid) FROM sc GROUP BY sid HAVING COUNT(cid) < (SELECT COUNT(cid) FROM course) )t
WHERE s.sid = t.sid
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 sid,Sname FROM Student,SC WHERE Student.sid=SC.sid AND cid IN (SELECT cid FROM SC WHERE sid=‘1001’);
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,(SELECT c.cid,AVG(score) avgs FROM sc,course c,teacher t WHERE sc.cid = c.cid AND
c.tid = t.tid AND t.tName = ‘叶平’ GROUP BY c.cid)sc_2 SET sc.score = sc_2.avgs WHERE sc.cid = sc_2.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 sid FROM SC WHERE cid IN (SELECT cid FROM SC WHERE sid=‘1002’)
GROUP BY sid HAVING COUNT()=(SELECT COUNT() FROM SC WHERE 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 sc.cid FROM course c ,teacher t WHERE sc.cid = c.cid AND c.tid = t.tid AND t.tName = ‘叶平’)

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 score FROM SC WHERE SC.sid=t.sid AND cid=‘004’) AS 数据库
,(SELECT score FROM SC WHERE SC.sid=t.sid AND cid=‘001’) AS 企业管理
,(SELECT score FROM SC WHERE SC.sid=t.sid AND cid=‘005’) AS 英语
,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩
FROM SC AS t
GROUP BY sid
ORDER BY AVG(t.score)
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 cid “课程ID”,MAX(score) “最高分”,MIN(score) “最低分” FROM sc GROUP BY 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排序
oracle>
SELECT t.cid AS 课程号,MAX(course.Cname)AS 课程名,nvl(AVG(score),0) AS 平均成绩
,100 * SUM(CASE WHEN nvl(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() AS 及格百分数
FROM SC T,Course
WHERE t.cid=course.cid
GROUP BY t.cid
ORDER BY 100 * SUM(CASE WHEN nvl(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() DESC
Mysql>
SELECT t.cid AS 课程号,MAX(course.Cname)AS 课程名,IFNULL(AVG(score),0) AS 平均成绩
,100 * SUM(CASE WHEN IFNULL(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() AS 及格百分数
FROM SC T,Course
WHERE t.cid=course.cid
GROUP BY t.cid
ORDER BY 100 * SUM(CASE WHEN IFNULL(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() 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 SUM(CASE WHEN cid =‘001’ THEN score ELSE 0 END)/SUM(CASE cid WHEN ‘001’ THEN 1 ELSE 0 END) AS 企业管理平均分
,100 * SUM(CASE WHEN cid = ‘001’ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN cid = ‘001’ THEN 1 ELSE 0 END) AS 企业管理及格百分数
,SUM(CASE WHEN cid = ‘002’ THEN score ELSE 0 END)/SUM(CASE cid WHEN ‘002’ THEN 1 ELSE 0 END) AS 马克思平均分
,100 * SUM(CASE WHEN cid = ‘002’ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN cid = ‘002’ THEN 1 ELSE 0 END) AS 马克思及格百分数
,SUM(CASE WHEN cid = ‘003’ THEN score ELSE 0 END)/SUM(CASE cid WHEN ‘003’ THEN 1 ELSE 0 END) AS UML平均分
,100 * SUM(CASE WHEN cid = ‘003’ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN cid = ‘003’ THEN 1 ELSE 0 END) AS UML及格百分数
,SUM(CASE WHEN cid = ‘004’ THEN score ELSE 0 END)/SUM(CASE cid WHEN ‘004’ THEN 1 ELSE 0 END) AS 数据库平均分
,100 * SUM(CASE WHEN cid = ‘004’ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN cid = ‘004’ THEN 1 ELSE 0 END) AS 数据库及格百分数
FROM SC
21、查询不同老师所教不同课程平均分从高到低显示
SELECT MAX(t.tid) “教师ID”,MAX(t.tName) “教师姓名”,c.cid “课程ID”, MAX(c.cName) “课程名称” ,AVG(sc.score) “平均成绩”
FROM sc,course c,teacher t WHERE sc.cid = c.cid AND c.tid = t.tid GROUP BY c.tid,c.cid
ORDER BY AVG(sc.score) 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 SC.cid AS 课程ID, Cname AS 课程名称
,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]
,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]
,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]
,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -]
FROM SC,Course
WHERE SC.cid=Course.cid
GROUP BY SC.cid,Cname;

26、查询每门课程被选修的学生数
SELECT cid,COUNT(sid) 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
SELECT SC.sid,Student.Sname,COUNT(cid) AS 选课数
FROM SC ,Student
WHERE SC.sid=Student.sid GROUP BY SC.sid ,Student.Sname HAVING COUNT(cid)=1;
28、查询男生、女生人数
SELECT COUNT(Ssex) AS 男生人数 FROM Student GROUP BY Ssex HAVING Ssex=‘男’;
SELECT COUNT(Ssex) AS 女生人数 FROM Student GROUP BY Ssex HAVING Ssex=‘女’;
29、查询姓“张”的学生名单
SELECT Sname FROM Student WHERE Sname LIKE ‘张%’;
30、查询同名同性学生名单，并统计同名人数
SELECT sName,sSex ,COUNT() FROM student GROUP BY sName,sSex HAVING COUNT() > 1
31、1981年出生的学生名单(注：Student表中Sage列的类型是DATETIME)
Mysql>
SELECT Sname, CONVERT(CHAR (11),DATEPART(YEAR,Sage)) AS age
FROM student
WHERE CONVERT(CHAR(11),DATEPART(YEAR,Sage))=‘1981’;
Oracle>
SELECT * FROM student WHERE SUBSTR(to_char(sage,‘yyyy-MM-dd’),1,4)= ‘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 cid,AVG(score) FROM SC GROUP BY cid ORDER BY AVG(score),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 Sname,SC.sid ,AVG(score)
FROM Student,SC
WHERE Student.sid=SC.sid GROUP BY SC.sid,Sname HAVING AVG(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 Sname,ISNULL(score,0)
FROM Student,SC,Course
WHERE SC.sid=Student.sid AND SC.cid=Course.cid AND Course.Cname='数据库’AND score <60;
35、查询所有学生的选课情况;
SELECT SC.sid,SC.cid,Sname,Cname
FROM SC,Student,Course
WHERE SC.sid=Student.sid AND SC.cid=Course.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 student.sid,student.Sname,SC.cid,SC.score
FROM student,Sc
WHERE SC.score>=70 AND SC.sid=student.sid;
37、查询不及格的课程，并按课程号从大到小排列
SELECT cid FROM sc WHERE scor e <60 ORDER BY 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 SC.sid,Student.Sname FROM SC,Student WHERE SC.sid=Student.sid AND Score>80 AND cid=‘003’;
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 Student.Sname,score
FROM Student,SC,Course C,Teacher
WHERE Student.sid=SC.sid AND SC.cid=C.cid AND C.tid=Teacher.tid AND Teacher.Tname=‘叶平’ AND SC.score=(SELECT MAX(score)FROM SC WHERE cid=C.cid );
41、查询各个课程及相应的选修人数
SELECT COUNT() FROM sc GROUP BY 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、查询每门功课成绩最好的前两名
SELECT *
FROM sc t1
WHERE (
SELECT COUNT(*)
FROM sc t2
WHERE t1.cid=t2.cid
AND t2.score>=t1.score
) <=2 ORDER BY t1.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，若人数相同，按课程号升序排列
SELECT cid “课程号”,COUNT() “选修人数” FROM sc GROUP BY cid HAVING COUNT() >10 ORDER BY COUNT(*) DESC,cid

45、检索至少选修两门课程的学生学号
SELECT sid
FROM sc
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 s.sName,c.cName, COUNT() FROM student s,course c, sc WHERE s.sid = sc.sid AND sc.cid = c.cid GROUP BY sc.cid HAVING COUNT() = (SELECT COUNT() 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 DISTINCT Sname FROM Student WHERE sid NOT IN (SELECT sid FROM Course,Teacher,SC WHERE Course.tid=Teacher.tid AND SC.cid=course.cid AND 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(score,0)) FROM SC WHERE sid IN (SELECT sid FROM SC WHERE score <60 GROUP BY sid HAVING COUNT(*)>2)GROUP BY sid;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
SELECT sid FROM SC WHERE cid='004’AND score <60 ORDER BY score DESC;
50、删除“1002”同学的“001”课程的成绩
DELETE FROM Sc WHERE sid=‘1002’ AND cid=‘001’;