MYSQL练习
mysql -u root -p show databases; create database larken; use larken; show tables; -- ---------------------------- -- Table structure for class -- ---------------------------- CREATE TABLE `class` ( `cid` int(11) NOT NULL AUTO_INCREMENT, `caption` varchar(32) NOT NULL, PRIMARY KEY (`cid`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of class -- ---------------------------- INSERT INTO `class` VALUES ('1', '高一一班'); INSERT INTO `class` VALUES ('2', '高一二班'); INSERT INTO `class` VALUES ('3', '高一三班'); INSERT INTO `class` VALUES ('4', '高一四班'); INSERT INTO `class` VALUES ('5', '高一五班'); -- ---------------------------- -- Table structure for student -- ---------------------------- CREATE TABLE `student` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `gender` char(1) NOT NULL, `class_id` int(11) NOT NULL, `sname` varchar(32) NOT NULL, PRIMARY KEY (`sid`), KEY `fk_class` (`class_id`), CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of student -- ---------------------------- INSERT INTO `student` VALUES ('1', '男', '1', 'aaa'); INSERT INTO `student` VALUES ('2', '女', '2', 'bbb'); INSERT INTO `student` VALUES ('3', '男', '4', 'ccc'); INSERT INTO `student` VALUES ('4', '男', '2', 'ddd'); INSERT INTO `student` VALUES ('5', '女', '5', 'eee'); INSERT INTO `student` VALUES ('6', '男', '1', 'fff'); INSERT INTO `student` VALUES ('7', '女', '4', 'ggg'); INSERT INTO `student` VALUES ('8', '男', '2', 'hhh'); INSERT INTO `student` VALUES ('9', '男', '1', 'iii'); INSERT INTO `student` VALUES ('10', '女', '5', 'jjj'); -- ---------------------------- -- Table structure for teacher -- ---------------------------- CREATE TABLE `teacher` ( `tid` int(11) NOT NULL AUTO_INCREMENT, `tname` varchar(32) NOT NULL, PRIMARY KEY (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of teacher -- ---------------------------- INSERT INTO `teacher` VALUES ('1', '张磊老师'); INSERT INTO `teacher` VALUES ('2', '李平老师'); INSERT INTO `teacher` VALUES ('3', '刘海燕老师'); INSERT INTO `teacher` VALUES ('4', '朱云海老师'); INSERT INTO `teacher` VALUES ('5', '李杰老师'); -- ---------------------------- -- Table structure for course -- ---------------------------- CREATE TABLE `course` ( `cid` int(11) NOT NULL AUTO_INCREMENT, `cname` varchar(32) NOT NULL, `teacher_id` int(11) NOT NULL, PRIMARY KEY (`cid`), KEY `fk_course_teacher` (`teacher_id`), CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of course -- ---------------------------- INSERT INTO `course` VALUES ('1', '语文', '1'); INSERT INTO `course` VALUES ('2', '数学', '2'); INSERT INTO `course` VALUES ('3', '外语', '3'); INSERT INTO `course` VALUES ('4', '物理', '4'); INSERT INTO `course` VALUES ('5', '化学', '5'); -- ---------------------------- -- Table structure for score -- ---------------------------- CREATE TABLE `score` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `student_id` int(11) NOT NULL, `course_id` int(11) NOT NULL, `num` int(11) NOT NULL, PRIMARY KEY (`sid`), KEY `fk_score_student` (`student_id`), KEY `fk_score_course` (`course_id`), CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`), CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) ) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of score -- ---------------------------- INSERT INTO `score` VALUES ('1', '1', '1', '78'); INSERT INTO `score` VALUES ('2', '2', '2', '91'); INSERT INTO `score` VALUES ('3', '3', '4', '66'); INSERT INTO `score` VALUES ('4', '4', '5', '83'); INSERT INTO `score` VALUES ('5', '5', '3', '68'); INSERT INTO `score` VALUES ('6', '6', '4', '99'); INSERT INTO `score` VALUES ('7', '7', '1', '77'); INSERT INTO `score` VALUES ('8', '8', '2', '66'); INSERT INTO `score` VALUES ('9', '9', '3', '87'); INSERT INTO `score` VALUES ('10', '10', '4', '99'); 查询条件 1、查询所有的课程的名称以及对应的任课老师姓名 SELECT cname,tname FROM course LEFT JOIN teacher on course.teacher_id=teacher.tid; 2、查询学生表中男女生各有多少人 SELECT gender 性别 ,COUNT(gender) 人数 from student GROUP BY gender; 3、查询物理成绩等于100的学生的姓名 SELECT sname from student where sid in (SELECT student_id from score LEFT JOIN course ON score.course_id=course.cid WHERE num=100 AND course.cname="物理"); 4、查询平均成绩大于八十分的同学的姓名和平均成绩 SELECT sname 姓名,平均成绩 from student RIGHT JOIN (SELECT student_id,avg(num) 平均成绩 from score GROUP BY student_id HAVING avg(num)>80) as A on student.sid=A.student_id; 5、查询所有学生的学号,姓名,选课数,总成绩 SELECT student_id 学号,sname 姓名,COUNT(course_id) 课程数,SUM(num) 总分 FROM score LEFT JOIN student ON score.student_id=student.sid GROUP BY student_id; 6、 查询姓李老师的个数 7、 查询没有报李平老师课的学生姓名 SELECT * FROM student WHERE sid not in (SELECT student_id FROM score WHERE course_id in (SELECT cid FROM course LEFT JOIN teacher ON teacher.tid=course.teacher_id WHERE tname like "李平%")) 8、 查询物理课程比生物课程高的学生的学号 SELECT * FROM (SELECT * FROM score LEFT JOIN course ON score.course_id=course.cid WHERE cname="生物") as A INNER JOIN (SELECT * FROM score LEFT JOIN course ON score.course_id=course.cid WHERE cname="物理") as B ON A.student_id=B.student_id WHERE a.num<b.num 9、 查询没有同时选修物理课程和体育课程的学生姓名 SELECT sname from student WHERE sid NOT IN (SELECT student_id FROM score LEFT JOIN course ON score.course_id=course.cid WHERE cname='体育' OR cname='物理' GROUP BY student_id HAVING COUNT(course_id)>1) ; 10、查询挂科超过两门(包括两门)的学生姓名和班级 SELECT sname,gender from student WHERE sid in (SELECT student_id from score WHERE num<60 GROUP BY student_id HAVING COUNT(student_id)>1); 11 、查询选修了所有课程的学生姓名 SELECT sid 学号,sname 姓名 from student WHERE sid in (SELECT student_id FROM score GROUP BY student_id HAVING COUNT(student_id)!= (SELECT COUNT(cid) FROM course)) 12、查询李平老师教的课程的所有成绩记录 SELECT * FROM score WHERE course_id NOT IN (SELECT cid from teacher INNER JOIN course on teacher.tid=course.teacher_id WHERE teacher.tname LIKE "李平%"); 13、查询全部学生都选修了的课程号和课程名 SELECT course_id from score GROUP BY course_id HAVING COUNT(course_id)=(SELECT COUNT(sid) FROM student); 14、查询每门课程被选修的次数 SELECT course_id,COUNT(course_id) from score GROUP BY course_id; 15、查询只选修了一门课程的学生姓名和学号 SELECT sid,sname FROM student WHERE sid in (SELECT student_id from score GROUP BY student_id HAVING COUNT(sid)=1); 16、查询所有学生考出的成绩并按从高到低排序(成绩去重) SELECT DISTINCT num FROM score ORDER BY num DESC; 17、查询平均成绩大于85的学生姓名和平均成绩 SELECT sname,AVG(num) FROM student LEFT JOIN score ON student.sid=score.student_id GROUP BY student_id HAVING AVG(num)>85; 18、查询生物成绩不及格的学生姓名和对应生物分数 SELECT sname 姓名,num 生物成绩 FROM score LEFT JOIN course ON score.course_id=course.cid LEFT JOIN student ON score.student_id=student.sid WHERE score.num<60 AND cname="生物"; 19、查询在所有选修了李平老师课程的学生中,这些课程(李平老师的课程,不是所有课程)平均成绩最高的学生姓名 SELECT student_id,avg(num),sname FROM score LEFT JOIN student ON score.student_id=student.sid WHERE course_id in (SELECT cid FROM course LEFT JOIN teacher ON teacher.tid=course.teacher_id WHERE tname LIKE "李平%") GROUP BY student_id ORDER BY AVG(num) DESC LIMIT 1