MySQL数据库-子查询-表联接（内/外）-综合练习

– 学生信息表
CREATE TABLE students(
studentid INT AUTO_INCREMENT PRIMARY KEY,-- 学号
studentName VARCHAR(20) NOT NULL,-- 姓名
gender CHAR(20),-- 性别
birthday DATE
)ENGINE=INNODB;
INSERT INTO students(studentname,gender,birthday) VALUES
(‘张三’,‘男’,‘1987-02-01’),
(‘李斯’,‘女’,‘1990-12-01’),
(‘王二’,‘男’,‘1988-09-01’),
(‘黎明’,‘男’,‘1991-08-01’);

– 老师信息表
CREATE TABLE teachers(
teacherid INT AUTO_INCREMENT NOT NULL PRIMARY KEY, – 老师编号
teacherName VARCHAR(20) NOT NULL-- 老师姓名
)ENGINE=INNODB;
INSERT INTO teachers(teacherName)
VALUES(‘张三’),(‘李四’),(‘王五’),(‘Jacky’),(‘Helen’),(‘Kevin’);

– 课程表
CREATE TABLE courses(
Courseid INT AUTO_INCREMENT NOT NULL, – 课程号
courseName VARCHAR(20) NOT NULL UNIQUE, – 课程名
TeacherID INT NOT NULL , – 教师编号
FOREIGN KEY (teacherID) REFERENCES teachers(teacherId),
PRIMARY KEY (courseid,teacherid)
)ENGINE=INNODB;
INSERT INTO courses(coursename, teacherID) VALUES
(‘pre’,4),(‘c’,4),(‘sql’,5),(‘java oo’,3),(‘oracle’,5),
(‘ooad’,3),(‘Web前端’,5),(‘Java web’,4),(‘Java EE’,3),(‘Android’,2),(‘毕业项目’,5),
(‘就业课’,1);

– 成绩表
CREATE TABLE scores(
studentid INT NOT NULL, – 学号
courseid INT NOT NULL, – 课程号
mark INT, – 成绩
PRIMARY KEY (studentid,courseid),
FOREIGN KEY (studentid) REFERENCES students(studentid),
FOREIGN KEY (courseid) REFERENCES Courses(CourseID)
)ENGINE=INNODB;
INSERT INTO scores(studentid,courseid,mark) VALUES
(1,1,60),(1,2,70),(1,3,80),(1,4,55),(1,5,100),(1,6,90),
(2,1,50),(2,2,70),(2,3,80),(2,4,55),(2,5,100),(2,6,90),(2,7,50),(2,8,70),(2,9,50),(2,10,55),(2,11,100),(2,12,30),
(3,1,90),(3,2,70),(3,3,80),(3,4,55),(3,5,100),(3,6,90),(3,7,90),(3,8,80),(3,9,90),(3,10,55),(3,11,100),(3,12,100),
(4,1,100),(4,2,70),(4,3,80),(4,4,55),(4,5,100),(4,6,90),(4,9,100),(4,10,90);

– 请编写SQL语句，完成如下任务:
– 1.查询课程"001"比课程"002"成绩高的所有学生的学号
SELECT s1.studentid as 学号 FROM (SELECT * FROM scores WHERE courseid=001)
s1 JOIN (SELECT * FROM scores WHERE courseid=002)
s2 ON s1.studentid=s2.studentid WHERE s1.mark>s2.mark

– 2.查询平均成绩大于60分的同学的学号和平均成绩
SELECT studentid AS 学号,AVG(mark) AS 平均成绩
FROM scores
GROUP BY studentid
HAVING AVG(mark)>60;

– 3.查询所有同学的学号、姓名、选课数、总成绩
SELECT xs.studentid AS 学号,xs.studentName AS 姓名,COUNT(cj.courseid) AS 选课数,SUM(cj.mark) AS 总成绩
FROM students xs JOIN scores cj ON xs.studentid=cj.studentid
GROUP BY xs.studentid;

– 4.查询姓“王”的老师的个数
SELECT COUNT(teacherid) AS 姓王的老师的个数
FROM teachers
WHERE teacherName LIKE ‘王%’;

– 5.查询没学过"张三"老师课的同学的学号、姓名
SELECT DISTINCT studentid AS 学号,studentName AS 姓名
FROM students
WHERE studentid NOT IN(
SELECT studentid FROM scores WHERE courseid IN(
SELECT kc.Courseid FROM courses kc JOIN teachers ls ON ls.teacherid=kc.TeacherID
WHERE ls.teacherName=‘张三’));

– 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 studentid AS 学号,studentName AS 姓名， FROM students
WHERE studentid IN(
SELECT s001.studentid FROM
(SELECT studentid FROM scores WHERE courseid=001) s001 JOIN
(SELECT studentid FROM scores WHERE courseid =002) s002
ON s001.studentid=s002.studentid
);

– 7.查询学过“Jacky”老师所教的所有课的同学的学号、姓名
SELECT stu.studentid AS 学号,stu.studentName AS 名称,zsstu.选了几门
FROM students stu JOIN
查询那些人选了Jacky的课选了几门计数
(SELECT studentid AS 学号,COUNT(courseid) AS 选了几门 FROM scores
WHERE courseid IN (-- 查询Jacky教了那些课输出编号表
SELECT Courseid FROM courses
WHERE TeacherID=(SELECT teacherid FROM teachers
WHERE teacherName=‘Jacky’)
)
GROUP BY studentid) zsstu ON stu.studentid=zsstu.学号
WHERE zsstu.选了几门=(-- 查询Jacky教了那些课输出编号表计数
SELECT COUNT(Courseid) FROM courses
WHERE TeacherID=(SELECT teacherid FROM teachers
WHERE teacherName=‘Jacky’)
)

– 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 DISTINCT xs.studentid AS 学号,xs.studentName AS 姓名
FROM students xs JOIN scores cj ON xs.studentid=cj.studentid
WHERE xs.studentid IN(
SELECT s1.studentid FROM (SELECT * FROM scores WHERE courseid=002) s1 JOIN (SELECT * FROM scores WHERE courseid=001) s2 ON s1.studentid=s2.studentid
WHERE s1.mark>s2.mark)

– 9.查询所有课程的成绩小于60分的同学的学号、姓名
SELECT xs.studentid AS 学号,xs.studentName AS 姓名
FROM students xs JOIN scores cj ON xs.studentid=cj.studentid
WHERE cj.studentid NOT IN(SELECT DISTINCT studentid FROM scores WHERE mark>=60)

– 10.列出sql成绩大于等于所有学生sql平均成绩的学生
SELECT xs.studentName AS 姓名, cj.mark AS 成绩
FROM students xs JOIN scores cj ON xs.studentid=cj.studentid
WHERE cj.mark>=(SELECT AVG(mark) FROM scores WHERE courseid=(SELECT Courseid FROM courses WHERE courseName=‘sql’))
AND cj.courseid=(SELECT Courseid FROM courses WHERE courseName=‘sql’);

– 11.列出没有上过“就业课”的同学
SELECT xs.studentName AS 姓名
FROM students xs JOIN scores cj ON xs.studentid=cj.studentid
WHERE xs.studentid NOT IN(SELECT studentid FROM scores WHERE courseid=(SELECT Courseid FROM courses WHERE courseName=‘就业课’))
GROUP BY xs.studentid;

– 12.列出“王五”老师所教授的课程有哪些？（列出课程名字，和老）师名字
SELECT kc.courseName AS 课程,ls.teacherName AS 老师姓名
FROM courses kc JOIN teachers ls ON kc.TeacherID=ls.teacherid
WHERE ls.teacherName=‘王五’;

– 13.列出被学生得到100分的课程有哪些？
SELECT DISTINCT kc.courseName AS 课程名,cj.mark AS 分数
FROM scores cj JOIN courses kc ON cj.courseid=kc.Courseid
WHERE cj.mark=100;

– 14.列出所有学生每门课程的考试成绩
SELECT xs.studentName AS 姓名,kc.courseName AS 课程,cj.mark AS 分数
FROM students xs,scores cj,courses kc
WHERE xs.studentid=cj.studentid AND cj.courseid=kc.Courseid
ORDER BY xs.studentid;

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