mysql常见面试题

Posted 2021-01-12 uncledrew

测试数据：

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : mysql
 Source Server Version : 50624
 Source Host           : localhost
 Source Database       : sqlexam

 Target Server Type    : MySQL
 Target Server Version : 50624
 File Encoding         : utf-8

 Date: 10/21/2016 06:46:46 AM
*/

SET NAMES utf8;
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) NOT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

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

-- ----------------------------
--  Table structure for `course`
-- ----------------------------
DROP TABLE IF EXISTS `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`
-- ----------------------------
BEGIN;
INSERT INTO `course` VALUES (‘1‘, ‘生物‘, ‘1‘), (‘2‘, ‘物理‘, ‘2‘), (‘3‘, ‘体育‘, ‘3‘), (‘4‘, ‘美术‘, ‘2‘);
COMMIT;

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

-- ----------------------------
--  Table structure for `student`
-- ----------------------------
DROP TABLE IF EXISTS `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`
-- ----------------------------
BEGIN;
INSERT INTO `student` VALUES (‘1‘, ‘男‘, ‘1‘, ‘理解‘), (‘2‘, ‘女‘, ‘1‘, ‘钢蛋‘), (‘3‘, ‘男‘, ‘1‘, ‘张三‘), (‘4‘, ‘男‘, ‘1‘, ‘张一‘), (‘5‘, ‘女‘, ‘1‘, ‘张二‘), (‘6‘, ‘男‘, ‘1‘, ‘张四‘), (‘7‘, ‘女‘, ‘2‘, ‘铁锤‘), (‘8‘, ‘男‘, ‘2‘, ‘李三‘), (‘9‘, ‘男‘, ‘2‘, ‘李一‘), (‘10‘, ‘女‘, ‘2‘, ‘李二‘), (‘11‘, ‘男‘, ‘2‘, ‘李四‘), (‘12‘, ‘女‘, ‘3‘, ‘如花‘), (‘13‘, ‘男‘, ‘3‘, ‘刘三‘), (‘14‘, ‘男‘, ‘3‘, ‘刘一‘), (‘15‘, ‘女‘, ‘3‘, ‘刘二‘), (‘16‘, ‘男‘, ‘3‘, ‘刘四‘);
COMMIT;

-- ----------------------------
--  Table structure for `teacher`
-- ----------------------------
DROP TABLE IF EXISTS `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`
-- ----------------------------
BEGIN;
INSERT INTO `teacher` VALUES (‘1‘, ‘张磊老师‘), (‘2‘, ‘李平老师‘), (‘3‘, ‘刘海燕老师‘), (‘4‘, ‘朱云海老师‘), (‘5‘, ‘李杰老师‘);
COMMIT;

SET FOREIGN_KEY_CHECKS = 1;

表结构和数据

-- 2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；
-- SELECT * from
-- (SELECT student_id,num as sw from student LEFT JOIN score on student.sid=score.student_id and score.course_id=1) as t1
-- LEFT JOIN
-- (SELECT student_id,num as wl from student LEFT JOIN score on student.sid=score.student_id and score.course_id=2) as t2
-- on t1.student_id=t2.student_id where sw>IF(ISNULL(wl),0,wl)
--
-- 3、查询平均成绩大于60分的同学的学号和平均成绩；
-- SELECT student_id,AVG(num) from score GROUP BY student_id HAVING AVG(num)>60
-- 4、查询所有同学的学号、姓名、选课数、总成绩；
-- SELECT student_id,sname,COUNT(course_id),SUM(num) from student LEFT JOIN score on student.sid=score.student_id GROUP BY student_id,sname
-- 5、查询姓“李”的老师的个数；
-- SELECT COUNT(*) 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；
-- SELECT * from student where sid not in
-- (SELECT DISTINCT(student_id) from score where score.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；
-- SELECT * from student WHERE student.sid in
-- (
-- SELECT t1.student_id as stuid FROM
-- (SELECT student_id from score where score.course_id=1) as t1
-- INNER JOIN
-- (SELECT student_id from score where score.course_id=2) as t2
-- ON t1.student_id=t2.student_id
-- )
--
-- 7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
-- SELECT
--     student_id,
--     sname
-- FROM
--     score
-- LEFT JOIN student ON score.student_id = student.sid
-- WHERE
--     course_id IN (1, 2)
-- GROUP BY
--     student_id
-- HAVING
--     COUNT(course_id) > 1
-- 8、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
-- SELECT
--     student_id,
--     sname
-- FROM
--     score
-- LEFT JOIN student ON score.student_id = student.sid
-- WHERE
--     course_id IN (
--         SELECT
--             cid
--         FROM
--             course
--         WHERE
--             teacher_id IN (
--                 SELECT
--                     tid
--                 FROM
--                     teacher
--                 WHERE
--                     tname = ‘李平老师‘
--             )
--     )
-- GROUP BY
--     student_id -- SELECT cid from course WHERE teacher_id in(SELECT tid from teacher WHERE tname=‘李平老师‘)
-- 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；
-- SELECT t1.student_id,t1.num as c1,t2.num as c2 ,sname from
-- (SELECT student_id,num from score where course_id=1) as t1
-- LEFT JOIN
-- (SELECT student_id,num from score where course_id=2) as t2
-- on t1.student_id=t2.student_id
-- LEFT JOIN student on t1.student_id=student.sid
-- WHERE t1.num>if(ISNULL(t2.num),0,t2.num)
-- 10、查询有课程成绩小于60分的同学的学号、姓名；
-- SELECT * 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,COUNT(course_id) from score GROUP BY student_id HAVING COUNT(course_id)<4
--
-- SELECT * from student LEFT JOIN score on student.sid=score.student_id
-- SELECT
--     *
-- FROM
--     student
-- WHERE
--     sid IN (
--         SELECT
--             student.sid
--         FROM
--             student
--         LEFT JOIN score ON student.sid = score.student_id
--         GROUP BY
--             student.sid
--         HAVING
--             COUNT(course_id) < 4
--     )
--
-- 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
--     *
-- FROM
--     student
-- WHERE
--     sid IN (
--         SELECT
--             student_id
--         FROM
--             score
--         WHERE
--             course_id IN (
--                 SELECT
--                     course_id
--                 FROM
--                     score
--                 WHERE
--                     student_id = 1
--             )
--         AND student_id != 1
--         GROUP BY
--             student_id
--     )
-- 13、查询至少学过学号为“001”同学所有课的其他同学学号和姓名；
-- SELECT
--     *
-- FROM
--     student
-- WHERE
--     sid IN (
--         SELECT
--             student_id
--         FROM
--             score
--         WHERE
--             course_id IN (
--                 SELECT
--                     course_id
--                 FROM
--                     score
--                 WHERE
--                     student_id = 1
--             )
--         AND student_id != 1
--         GROUP BY
--             student_id
--         HAVING
--             COUNT(student_id) >= 3
--     )
-- 14、查询和“002”号的同学学习的课程完全相同的其他同学学号和姓名；

-- SELECT
--     student_id,
--     COUNT(student_id)
-- FROM
--     score
-- WHERE
--     course_id IN (
--         SELECT
--             course_id
--         FROM
--             score
--         WHERE
--             student_id = 2
--     )
-- AND student_id IN (
--     SELECT
--         student_id
--     FROM
--         score
--     GROUP BY
--         student_id
--     HAVING
--         COUNT(student_id) = (
--             SELECT
--                 COUNT(student_id)
--             FROM
--                 score
--             WHERE
--                 student_id = 2
--             GROUP BY
--                 student_id
--         )
-- )
-- GROUP BY
--     student_id
-- HAVING
--     COUNT(student_id) > 2
--

-- 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；

-- SELECT * from
-- (SELECT student_id, num as ‘生物‘ from score where course_id=1) as t1
-- LEFT JOIN
-- (SELECT student_id, num as ‘物理‘ from score where course_id=2) as t2 ON t1.student_id=t2.student_id
-- LEFT JOIN
-- (SELECT student_id, num as ‘体育‘ from score where course_id=3) as t3 ON t1.student_id=t3.student_id
-- LEFT JOIN
-- (SELECT student_id,AVG(num) as ‘平均分‘ from score WHERE course_id in(1,2,3) GROUP BY student_id ) as t4 on t1.student_id=t4.student_id


-- 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 course_id,MAX(num) as ‘最高分‘,MIN(num) as ‘最低分‘ from score GROUP BY course_id

-- 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 course_id,AVG(num) as ‘平均分‘,SUM(case WHEN num>=60 THEN 1 ELSE 0 END)*100/COUNT(course_id) as ‘及格率‘ from score GROUP BY course_id


-- 20、课程平均分从高到低显示（现实任课老师）；
-- SELECT course_id,AVG(num),tname from score LEFT JOIN course ON score.course_id=course.cid LEFT JOIN teacher on course.teacher_id=teacher.tid GROUP BY course_id

-- 21、查询各科成绩前三名的记录:(不考虑成绩并列情况)

-- select score.sid,score.course_id,score.num,T.first_num,T.second_num from score left join
--     (
--     select
--         sid,
--         (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0,1) as first_num,
--         (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 3,1) as second_num
--     from
--         score as s1
--     ) as T
--     on score.sid =T.sid
--     where score.num <= T.first_num and score.num >= T.second_num
--

-- 22、查询每门课程被选修的学生数；
-- SELECT cname,COUNT(course_id) as ‘人数‘ from score LEFT JOIN course on score.course_id=course.cid GROUP BY course_id

-- 23、查询出只选修了一门课程的全部学生的学号和姓名；
-- SELECT student_id,COUNT(student_id),sname from score  LEFT JOIN student on score.student_id=student.sid GROUP BY student_id having COUNT(student_id)=1

-- 24、查询男生、女生的人数；
-- SELECT gender,COUNT(gender) from student GROUP BY gender

-- 25、查询姓“张”的学生名单；
-- select sname from student where sname like ‘张%‘;

-- 26、查询同名同姓学生名单，并统计同名人数；
-- select sname,count(1) as count from student group by sname;

-- 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；

-- SELECT course_id,AVG(num) as a from score GROUP BY course_id ORDER BY a ASC,course_id DESC

-- 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；
-- SELECT student_id,AVG(num) from score GROUP BY student_id HAVING AVG(num)>80

-- 29、查询课程名称为“数学”，且分数低于60的学生姓名和分数；

-- SELECT * from score LEFT JOIN course on score.course_id=course.cid
-- LEFT JOIN student on score.student_id=student.sid WHERE cname=‘物理‘ and num>60

-- 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；
--
-- SELECT tname,student_id ,num from score LEFT JOIN course on score.course_id=course.cid
-- LEFT JOIN teacher on course.teacher_id=teacher.tid
-- WHERE tname=‘张磊老师‘ GROUP BY tname,student_id,num ORDER BY num DESC LIMIT 2
--
-- 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；

-- SELECT num,course_id from score LEFT JOIN student on score.student_id=student.sid GROUP BY num,course_id ORDER BY num

-- 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
-- SELECT * FROM
-- (SELECT student_id,COUNT(student_id) as count1 from score GROUP BY student_id) as t1
-- LEFT JOIN
-- (SELECT student_id,COUNT(student_id) as count2 from score where course_id not in(SELECT cid from course LEFT JOIN teacher on course.teacher_id=teacher.tid WHERE tname=‘李平老师‘
-- ) GROUP BY student_id) as t2
-- on t1.student_id=t2.student_id
-- WHERE t1.count1=t2.count2
--
-- 39、查询两门以上不及格课程的同学的学号及其平均成绩；
--  
--     select student_id,count(1) from score where num < 60 group by student_id having count(1) > 2
--  
-- 40、检索“004”课程分数小于60，按分数降序排列的同学学号；
--     select student_id from score where num< 60 and course_id = 4 order by num desc;
--  
-- 41、删除“002”同学的“001”课程的成绩；
--     delete from score where course_id = 1 and student_id = 2

参考文章：https://www.cnblogs.com/wupeiqi/articles/5748496.html#commentform