MySQL练习题

一、表关系

导出现有数据库的数据：

• mysqldump -u用户名 -p密码 数据库名称 >导出文件路径 + 文件名      # 表结构 + 数据
• mysqldump -u用户名 -p密码 -d 数据库名称 >导出文件路径 + 文件名  # 表结构

将文件中的数据导入数据库：

• mysqldump -uroot -p密码  数据库名称 < 文件路径 + 文件名

二、练习题

1、自行创建测试数据

/*
 Navicat Premium Data Transfer

 Source Server         : 10.0.100.187
 Source Server Type    : MySQL
 Source Server Version : 50625
 Source Host           : 10.0.100.187:3306
 Source Schema         : test

 Target Server Type    : MySQL
 Target Server Version : 50625
 File Encoding         : 65001

 Date: 11/03/2019 14:36:33
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for class
-- ----------------------------
DROP TABLE IF EXISTS `class`;
CREATE TABLE `class`  (
  `cid` int(11) NOT NULL AUTO_INCREMENT,
  `caption` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  PRIMARY KEY (`cid`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of class
-- ----------------------------
INSERT INTO `class` VALUES (1, '三年二班');
INSERT INTO `class` VALUES (2, '三年三班');
INSERT INTO `class` VALUES (3, '一年二班');
INSERT INTO `class` VALUES (4, '二年九班');

-- ----------------------------
-- Table structure for course
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course`  (
  `cid` int(11) NOT NULL AUTO_INCREMENT,
  `cname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `teacher_id` int(11) NOT NULL,
  PRIMARY KEY (`cid`) USING BTREE,
  INDEX `fk_course_teacher`(`teacher_id`) USING BTREE,
  CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of course
-- ----------------------------
INSERT INTO `course` VALUES (1, '生物', 1);
INSERT INTO `course` VALUES (2, '物理', 2);
INSERT INTO `course` VALUES (3, '体育', 3);
INSERT INTO `course` VALUES (4, '美术', 2);

-- ----------------------------
-- Table structure for score
-- ----------------------------
DROP TABLE IF EXISTS `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`) USING BTREE,
  INDEX `fk_score_student`(`student_id`) USING BTREE,
  INDEX `fk_score_course`(`course_id`) USING BTREE,
  CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`) ON DELETE RESTRICT ON UPDATE RESTRICT,
  CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB AUTO_INCREMENT = 53 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of score
-- ----------------------------
INSERT INTO `score` VALUES (1, 1, 1, 10);
INSERT INTO `score` VALUES (2, 1, 2, 9);
INSERT INTO `score` VALUES (5, 1, 4, 66);
INSERT INTO `score` VALUES (6, 2, 1, 8);
INSERT INTO `score` VALUES (8, 2, 3, 68);
INSERT INTO `score` VALUES (9, 2, 4, 99);
INSERT INTO `score` VALUES (10, 3, 1, 77);
INSERT INTO `score` VALUES (11, 3, 2, 66);
INSERT INTO `score` VALUES (12, 3, 3, 87);
INSERT INTO `score` VALUES (13, 3, 4, 99);
INSERT INTO `score` VALUES (14, 4, 1, 79);
INSERT INTO `score` VALUES (15, 4, 2, 11);
INSERT INTO `score` VALUES (16, 4, 3, 67);
INSERT INTO `score` VALUES (17, 4, 4, 100);
INSERT INTO `score` VALUES (18, 5, 1, 79);
INSERT INTO `score` VALUES (19, 5, 2, 11);
INSERT INTO `score` VALUES (20, 5, 3, 67);
INSERT INTO `score` VALUES (21, 5, 4, 100);
INSERT INTO `score` VALUES (22, 6, 1, 9);
INSERT INTO `score` VALUES (23, 6, 2, 100);
INSERT INTO `score` VALUES (24, 6, 3, 67);
INSERT INTO `score` VALUES (25, 6, 4, 100);
INSERT INTO `score` VALUES (26, 7, 1, 9);
INSERT INTO `score` VALUES (27, 7, 2, 100);
INSERT INTO `score` VALUES (28, 7, 3, 67);
INSERT INTO `score` VALUES (29, 7, 4, 88);
INSERT INTO `score` VALUES (30, 8, 1, 9);
INSERT INTO `score` VALUES (31, 8, 2, 100);
INSERT INTO `score` VALUES (32, 8, 3, 67);
INSERT INTO `score` VALUES (33, 8, 4, 88);
INSERT INTO `score` VALUES (34, 9, 1, 91);
INSERT INTO `score` VALUES (35, 9, 2, 88);
INSERT INTO `score` VALUES (36, 9, 3, 67);
INSERT INTO `score` VALUES (37, 9, 4, 22);
INSERT INTO `score` VALUES (38, 10, 1, 90);
INSERT INTO `score` VALUES (39, 10, 2, 77);
INSERT INTO `score` VALUES (40, 10, 3, 43);
INSERT INTO `score` VALUES (41, 10, 4, 87);
INSERT INTO `score` VALUES (42, 11, 1, 90);
INSERT INTO `score` VALUES (43, 11, 2, 77);
INSERT INTO `score` VALUES (44, 11, 3, 43);
INSERT INTO `score` VALUES (45, 11, 4, 87);
INSERT INTO `score` VALUES (46, 12, 1, 90);
INSERT INTO `score` VALUES (47, 12, 2, 77);
INSERT INTO `score` VALUES (48, 12, 3, 43);
INSERT INTO `score` VALUES (49, 12, 4, 87);
INSERT INTO `score` VALUES (52, 13, 3, 87);

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student`  (
  `sid` int(11) NOT NULL AUTO_INCREMENT,
  `gender` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `class_id` int(11) NOT NULL,
  `sname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  PRIMARY KEY (`sid`) USING BTREE,
  INDEX `fk_class`(`class_id`) USING BTREE,
  CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB AUTO_INCREMENT = 17 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of student
-- ----------------------------
INSERT INTO `student` VALUES (1, '男', 1, '理解');
INSERT INTO `student` VALUES (2, '女', 1, '钢蛋');
INSERT INTO `student` VALUES (3, '男', 1, '张三');
INSERT INTO `student` VALUES (4, '男', 1, '张一');
INSERT INTO `student` VALUES (5, '女', 1, '张二');
INSERT INTO `student` VALUES (6, '男', 1, '张四');
INSERT INTO `student` VALUES (7, '女', 2, '铁锤');
INSERT INTO `student` VALUES (8, '男', 2, '李三');
INSERT INTO `student` VALUES (9, '男', 2, '李一');
INSERT INTO `student` VALUES (10, '女', 2, '李二');
INSERT INTO `student` VALUES (11, '男', 2, '李四');
INSERT INTO `student` VALUES (12, '女', 3, '如花');
INSERT INTO `student` VALUES (13, '男', 3, '刘三');
INSERT INTO `student` VALUES (14, '男', 3, '刘一');
INSERT INTO `student` VALUES (15, '女', 3, '刘二');
INSERT INTO `student` VALUES (16, '男', 3, '刘四');

-- ----------------------------
-- Table structure for teacher
-- ----------------------------
DROP TABLE IF EXISTS `teacher`;
CREATE TABLE `teacher`  (
  `tid` int(11) NOT NULL AUTO_INCREMENT,
  `tname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  PRIMARY KEY (`tid`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 6 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- 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');

SET FOREIGN_KEY_CHECKS = 1;

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；

3、查询平均成绩大于60分的同学的学号、姓名和平均成绩；

-- 方法一
SELECT student_id,sname,AVG(num) FROM score a,student b
WHERE a.student_id = b.sid
GROUP BY student_id HAVING AVG(num) > 60;

-- 方法二
SELECT student_id,sname,AVG(num) FROM score a LEFT JOIN student b 
ON a.student_id = b.sid
GROUP BY student_id HAVING AVG(num) > 60;

-- 方法三
SELECT T.student_id,student.sname,T.A FROM 
(SELECT student_id,AVG(num) AS A FROM score GROUP BY student_id HAVING AVG(num)>60) as T
LEFT JOIN student ON T.student_id = student.sid;

4、查询所有同学的学号、姓名、选课数、总成绩；

-- 方法一
SELECT a.student_id,b.sname,COUNT(a.course_id),SUM(a.num) FROM score a 
LEFT JOIN student b ON a.student_id = b.sid
GROUP BY a.student_id;

-- 方法二
SELECT a.student_id,b.sname,COUNT(course_id),SUM(num) FROM score a,student b 
WHERE a.student_id = b.sid
GROUP BY a.student_id;

5、查询姓“李”的老师的个数；

SELECT COUNT(1) FROM teacher WHERE tname LIKE '李%';

6、查询没学过“李平”老师课的同学的学号、姓名；

思路：
    先查到“李平老师”老师教的所有课ID
    获取选过课的所有学生ID
    学生表中筛选

SELECT sid,sname FROM student WHERE sid NOT IN(
    SELECT DISTINCT student_id FROM score WHERE course_id IN(
        SELECT cid FROM course LEFT JOIN teacher ON course.teacher_id = teacher.tid WHERE tname = '李平老师'));

7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

思路：
    先查到既选择001又选择002课程的所有同学
    根据学生进行分组，如果课程数量大于1，表示两门均已选择

SELECT student_id,sname FROM
    (SELECT student_id FROM score WHERE course_id = 1 or course_id = 2
        GROUP BY student_id
        HAVING COUNT(student_id) > 1) as B
    LEFT JOIN student ON B.student_id = student.sid;

8、查询学过“李平”老师所教的所有课的同学的学号、姓名；

思路：
    先查到“李平老师”老师教的所有课ID
    再查到学习过李平老师任意一门课程的student_id
    根据学生进行分组，如果课程数量等于李平老师教的所有课程数量，表示两门都学习了
    然后和student表联合查询展示student_id和sname

SELECT student_id,sname FROM
    (SELECT student_id FROM score WHERE course_id IN
        (SELECT cid FROM course LEFT JOIN teacher ON course.teacher_id = teacher.tid
            WHERE teacher.tname = '李平老师')
    GROUP BY student_id
    HAVING count(student_id) = (SELECT count(cid) FROM course LEFT JOIN teacher ON course.teacher_id = teacher.tid
            WHERE teacher.tname = '李平老师' )) as B 
LEFT JOIN student ON B.student_id = student.sid;

9、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；

10、查询有课程成绩小于60分的同学的学号、姓名；

SELECT sid,sname FROM student WHERE sid IN(
    SELECT DISTINCT student_id FROM score WHERE num < 60);

11、查询没有学全所有课的同学的学号、姓名；

SELECT student_id,sname,COUNT(course_id) FROM score
LEFT JOIN student ON score.student_id = student.sid
GROUP BY student_id
HAVING COUNT(course_id) < (SELECT COUNT(1) FROM course);

12、查询至少有一门课与学号为“001”的同学所学相同的同学的学号和姓名；

SELECT student_id,sname FROM score LEFT JOIN student ON score.student_id = student.sid
WHERE student_id !=1 AND course_id IN
    (SELECT course_id FROM score WHERE student_id = 1)
GROUP BY student_id;

13、查询学过学号为“001”同学所有课程的其他同学学号和姓名；

SELECT student_id,sname FROM score LEFT JOIN student ON score.student_id = student.sid
WHERE student_id !=1 AND course_id IN
    (SELECT course_id FROM score WHERE student_id = 1)
GROUP BY student_id
HAVING COUNT(course_id) = (SELECT COUNT(1) FROM score WHERE student_id = 1);

14、查询和“003”号的同学学习的课程完全相同的其他同学学号和姓名；

思路：
    课程数量和003号同学一样
    课程交集和003号同学所学课程一样

SELECT student_id,sname,COUNT(course_id) FROM score LEFT JOIN student ON score.student_id = student.sid
WHERE student_id IN
-- 课程数量和003号同学一样
(SELECT student_id FROM score WHERE student_id != 3 GROUP BY student_id HAVING COUNT(course_id) = (SELECT COUNT(1) FROM score WHERE student_id = 3))
-- 课程交集和003号同学所学课程一样
AND course_id IN (SELECT course_id FROM score WHERE student_id = 3)
GROUP BY student_id
HAVING COUNT(course_id) = (SELECT COUNT(1) FROM score WHERE student_id = 3);

15、删除学习“叶平”老师课的SC表记录；

16、向SC表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“002”课程的同学学号；②插入“002”号课程的平均成绩； 

17、按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；

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；

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；

20、课程平均分从高到低显示（现实任课老师）；

21、查询各科成绩前三名的记录:(不考虑成绩并列情况) 

22、查询每门课程被选修的学生数；

23、查询出只选修了一门课程的全部学生的学号和姓名；

24、查询男生、女生的人数；

25、查询姓“张”的学生名单；

26、查询同名同姓学生名单，并统计同名人数；

27、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；

28、查询平均成绩大于85的所有学生的学号、姓名和平均成绩；

29、查询课程名称为“数学”，且分数低于60的学生姓名和分数；

30、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； 

31、求选了课程的学生人数

32、查询选修“杨艳”老师所授课程的学生中，成绩最高的学生姓名及其成绩；

33、查询各个课程及相应的选修人数；

34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；

35、查询每门课程成绩最好的前两名；

36、检索至少选修两门课程的学生学号；

37、查询全部学生都选修的课程的课程号和课程名；

38、查询没学过“叶平”老师讲授的任一门课程的学生姓名；

39、查询两门以上不及格课程的同学的学号及其平均成绩；

40、检索“004”课程分数小于60，按分数降序排列的同学学号；

41、删除“002”同学的“001”课程的成绩；