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這期內容當中小編將會給大家帶來有關如何進行mysql多表查詢，文章內容豐富且以專業的角度為大家分析和敘述，閱讀完這篇文章希望大家可以有所收獲。
一、準備數據庫
init.sql文件內容如下：
/*
數據導入：
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', '體育', '3'), ('4', '美術', '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', '鋼蛋'), ('3', '男', '1', '張三'), ('4', '男', '1', '張一'), ('5', '女', '1', '張二'), ('6', '男', '1', '張四'), ('7', '女', '2', '鐵錘'), ('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', '劉三'), ('14', '男', '3', '劉一'), ('15', '女', '3', '劉二'), ('16', '男', '3', '劉四');
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', '張磊老師'), ('2', '李平老師'), ('3', '劉海燕老師'), ('4', '朱云海老師'), ('5', '李杰老師');
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;1、創建數據庫并導入數據
mysql> create database db1;
mysql> create database db1;
mysql> use db1;
mysql> source /root/init.sql
2、查看表
mysql> show tables; +---------------+ | Tables_in_db1 | +---------------+ | class | | course | | score | | student | | teacher | +---------------+ mysql> select * from class; +-----+--------------+ | cid | caption | +-----+--------------+ | 1 | 三年二班 | | 2 | 三年三班 | | 3 | 一年二班 | | 4 | 二年九班 | +-----+--------------+ mysql> select * from course; +-----+--------+------------+ | cid | cname | teacher_id | +-----+--------+------------+ | 1 | 生物 | 1 | | 2 | 物理 | 2 | | 3 | 體育 | 3 | | 4 | 美術 | 2 | +-----+--------+------------+ mysql> select * from teacher; +-----+-----------------+ | tid | tname | +-----+-----------------+ | 1 | 張磊老師 | | 2 | 李平老師 | | 3 | 劉海燕老師 | | 4 | 朱云海老師 | | 5 | 李杰老師 | +-----+-----------------+ mysql> select * from student; +-----+--------+----------+--------+ | sid | gender | class_id | sname | +-----+--------+----------+--------+ | 1 | 男 | 1 | 理解 | | 2 | 女 | 1 | 鋼蛋 | | 3 | 男 | 1 | 張三 | | 4 | 男 | 1 | 張一 | | 5 | 女 | 1 | 張二 | | 6 | 男 | 1 | 張四 | | 7 | 女 | 2 | 鐵錘 | | 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 | 劉三 | | 14 | 男 | 3 | 劉一 | | 15 | 女 | 3 | 劉二 | | 16 | 男 | 3 | 劉四 | +-----+--------+----------+--------+ mysql> select * from score; +-----+------------+-----------+-----+ | sid | student_id | course_id | num | +-----+------------+-----------+-----+ | 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 | +-----+------------+-----------+-----+
二、操作練習
1、查詢所有的課程的名稱以及對應的任課老師姓名
SELECT course.cname,teacher.tname FROM course INNER JOIN teacher ON course.teacher_id = teacher.tid; SELECT course.cname,teacher.tname FROM course JOIN teacher ON course.teacher_id = teacher.tid; +--------+-----------------+ | cname | tname | +--------+-----------------+ | 生物 | 張磊老師 | | 物理 | 李平老師 | | 美術 | 李平老師 | | 體育 | 劉海燕老師 | +--------+-----------------+
2、查詢學生表中男女生各有多少人
SELECT gender 性別,count(1) 人數 FROM student GROUP BY gender; +--------+--------+ | 性別 | 人數 | +--------+--------+ | 女 | 6 | | 男 | 10 | +--------+--------+
3、查詢物理成績等于100的學生的姓名
SELECT student.sname FROM student WHERE sid IN ( SELECT student_id FROM score INNER JOIN course ON score.course_id = course.cid WHERE course.cname = '物理' AND score.num = 100); +--------+ | sname | +--------+ | 張四 | | 鐵錘 | | 李三 | +--------+
4、查詢平均成績大于八十分的同學的姓名和平均成績
SELECT student.sname,t1.avg_num FROM student INNER JOIN ( SELECT student_id,avg(num) AS avg_num FROM score GROUP BY student_id HAVING avg(num) > 80) AS t1 ON student.sid = t1.student_id; +--------+---------+ | sname | avg_num | +--------+---------+ | 張三 | 82.2500 | | 劉三 | 87.0000 | +--------+---------+ SELECT student.sname, avg(num) AS avg_num FROM score JOIN student ON student.sid = score.student_id GROUP BY student_id HAVING avg_num > 80;
5、查詢所有學生的學號，姓名，選課數，總成績
SELECT student.sid,student.sname,t1.course_num,t1.total_num FROM student LEFT JOIN ( SELECT student_id,COUNT(course_id) course_num,sum(num) total_num FROM score GROUP BY student_id) AS t1 ON student.sid = t1.student_id; +-----+--------+------------+-----------+ | sid | sname | course_num | total_num | +-----+--------+------------+-----------+ | 1 | 理解 | 3 | 85 | | 2 | 鋼蛋 | 3 | 175 | | 3 | 張三 | 4 | 329 | | 4 | 張一 | 4 | 257 | | 5 | 張二 | 4 | 257 | | 6 | 張四 | 4 | 276 | | 7 | 鐵錘 | 4 | 264 | | 8 | 李三 | 4 | 264 | | 9 | 李一 | 4 | 268 | | 10 | 李二 | 4 | 297 | | 11 | 李四 | 4 | 297 | | 12 | 如花 | 4 | 297 | | 13 | 劉三 | 1 | 87 | | 14 | 劉一 | NULL | NULL | | 15 | 劉二 | NULL | NULL | | 16 | 劉四 | NULL | NULL | +-----+--------+------------+-----------+
6、 查詢姓李老師的個數
SELECT count(tid) FROM teacher WHERE tname LIKE '李%'; +------------+ | count(tid) | +------------+ | 2 | +------------+
7、 查詢沒有報李平老師課的學生姓名
SELECT student.sname FROM student WHERE sid NOT IN ( SELECT DISTINCT student_id FROM score WHERE course_id IN ( SELECT course.cid FROM course INNER JOIN teacher ON course.teacher_id = teacher.tid WHERE teacher.tname = '李平老師' )); +--------+ | sname | +--------+ | 劉三 | | 劉一 | | 劉二 | | 劉四 | +--------+
8、 查詢物理課程比生物課程高的學生的學號
SELECT t1.student_id FROM (SELECT student_id,num FROM score WHERE course_id = (SELECT cid FROM course WHERE cname = '物理')) AS t1 INNER JOIN ( SELECT student_id,num FROM score WHERE course_id = (SELECT cid FROM course WHERE cname = '生物') ) AS t2 ON t1.student_id = t2.student_id WHERE t1.num > t2.num; +------------+ | student_id | +------------+ | 6 | | 7 | | 8 | +------------+
9、 查詢沒有同時選修物理課程和體育課程的學生姓名
SELECT student.sname FROM student WHERE sid IN ( SELECT student_id FROM score WHERE course_id IN (SELECT cid FROM course WHERE cname = '物理' OR cname = '體育') GROUP BY student_id HAVING COUNT(course_id) = 1); +--------+ | sname | +--------+ | 理解 | | 鋼蛋 | | 劉三 | +--------+
10、查詢掛科超過兩門(包括兩門)的學生姓名和班級
SELECT student.sname,class.caption FROM student INNER JOIN ( SELECT student_id FROM score WHERE num < 60 GROUP BY student_id HAVING count(course_id) >= 2) AS t1 INNER JOIN class ON student.sid = t1.student_id AND student.class_id = class.cid; +--------+--------------+ | sname | caption | +--------+--------------+ | 理解 | 三年二班 | +--------+--------------+
11、查詢選修了所有課程的學生姓名
SELECT student.sname FROM student WHERE sid IN ( SELECT student_id FROM score GROUP BY student_id HAVING COUNT(course_id) = (SELECT count(cid) FROM course)); +--------+ | sname | +--------+ | 張三 | | 張一 | | 張二 | | 張四 | | 鐵錘 | | 李三 | | 李一 | | 李二 | | 李四 | | 如花 | +--------+
12、查詢李平老師教的課程的所有成績記錄
SELECT * FROM score WHERE course_id IN (SELECT cid FROM course INNER JOIN teacher ON course.teacher_id = teacher.tid WHERE teacher.tname = '李平老師'); +-----+------------+-----------+-----+ | sid | student_id | course_id | num | +-----+------------+-----------+-----+ | 2 | 1 | 2 | 9 | | 11 | 3 | 2 | 66 | | 15 | 4 | 2 | 11 | | 19 | 5 | 2 | 11 | | 23 | 6 | 2 | 100 | | 27 | 7 | 2 | 100 | | 31 | 8 | 2 | 100 | | 35 | 9 | 2 | 88 | | 39 | 10 | 2 | 77 | | 43 | 11 | 2 | 77 | | 47 | 12 | 2 | 77 | | 5 | 1 | 4 | 66 | | 9 | 2 | 4 | 99 | | 13 | 3 | 4 | 99 | | 17 | 4 | 4 | 100 | | 21 | 5 | 4 | 100 | | 25 | 6 | 4 | 100 | | 29 | 7 | 4 | 88 | | 33 | 8 | 4 | 88 | | 37 | 9 | 4 | 22 | | 41 | 10 | 4 | 87 | | 45 | 11 | 4 | 87 | | 49 | 12 | 4 | 87 | +-----+------------+-----------+-----+
13、查詢全部學生都選修了的課程號和課程名
SELECT cid,cname FROM course WHERE cid IN ( SELECT course_id FROM score GROUP BY course_id HAVING COUNT(student_id) = (SELECT COUNT(sid) FROM student));
14、查詢每門課程被選修的次數
SELECT course_id,COUNT(student_id) FROM score GROUP BY course_id; +-----------+-------------------+ | course_id | COUNT(student_id) | +-----------+-------------------+ | 1 | 12 | | 2 | 11 | | 3 | 12 | | 4 | 12 | +-----------+-------------------+
15、查詢之選修了一門課程的學生姓名和學號
SELECT sid,sname FROM student WHERE sid IN (SELECT student_id FROM score GROUP BY student_id HAVING COUNT(course_id) = 1); +-----+--------+ | sid | sname | +-----+--------+ | 13 | 劉三 | +-----+--------+
16、查詢所有學生考出的成績并按從高到低排序（成績去重）
SELECT DISTINCT num FROM score ORDER BY num DESC; +-----+ | num | +-----+ | 100 | | 99 | | 91 | | 90 | | 88 | | 87 | | 79 | | 77 | | 68 | | 67 | | 66 | | 43 | | 22 | | 11 | | 10 | | 9 | | 8 | +-----+
17、查詢平均成績大于85的學生姓名和平均成績
SELECT sname,t1.avg_num FROM student INNER JOIN ( SELECT student_id,avg(num) avg_num FROM score GROUP BY student_id HAVING AVG(num) > 85 ) t1 ON student.sid = t1.student_id; +--------+---------+ | sname | avg_num | +--------+---------+ | 劉三 | 87.0000 | +--------+---------+
18、查詢生物成績不及格的學生姓名和對應生物分數
SELECT sname 姓名,num 生物成績 FROM score LEFT JOIN course ON score.course_id = course.cid LEFT JOIN student ON score.student_id = student.sid WHERE course.cname = '生物' AND score.num < 60; +--------+--------------+ | 姓名 | 生物成績 | +--------+--------------+ | 理解 | 10 | | 鋼蛋 | 8 | | 張四 | 9 | | 鐵錘 | 9 | | 李三 | 9 | +--------+--------------+
19、查詢在所有選修了李平老師課程的學生中，這些課程(李平老師的課程，不是所有課程)平均成績最高的學生姓名
SELECT sname FROM student WHERE sid = ( SELECT student_id FROM score WHERE course_id IN ( SELECT course.cid FROM course INNER JOIN teacher ON course.teacher_id = teacher.tid WHERE teacher.tname = '李平老師') GROUP BY student_id ORDER BY AVG(num) DESC LIMIT 1 ); +--------+ | sname | +--------+ | 張四 | +--------+
20、查詢每門課程成績最好的前兩名學生姓名
#查看每門課程按照分數排序的信息，為下列查找正確與否提供依據 SELECT * FROM score ORDER BY course_id,num DESC; +-----+------------+-----------+-----+ | sid | student_id | course_id | num | +-----+------------+-----------+-----+ | 34 | 9 | 1 | 91 | | 46 | 12 | 1 | 90 | | 42 | 11 | 1 | 90 | | 38 | 10 | 1 | 90 | | 14 | 4 | 1 | 79 | | 18 | 5 | 1 | 79 | | 10 | 3 | 1 | 77 | | 1 | 1 | 1 | 10 | | 30 | 8 | 1 | 9 | | 26 | 7 | 1 | 9 | | 22 | 6 | 1 | 9 | | 6 | 2 | 1 | 8 | | 31 | 8 | 2 | 100 | | 23 | 6 | 2 | 100 | | 27 | 7 | 2 | 100 | | 35 | 9 | 2 | 88 | | 47 | 12 | 2 | 77 | | 43 | 11 | 2 | 77 | | 39 | 10 | 2 | 77 | | 11 | 3 | 2 | 66 | | 19 | 5 | 2 | 11 | | 15 | 4 | 2 | 11 | | 2 | 1 | 2 | 9 | | 52 | 13 | 3 | 87 | | 12 | 3 | 3 | 87 | | 8 | 2 | 3 | 68 | | 20 | 5 | 3 | 67 | | 36 | 9 | 3 | 67 | | 16 | 4 | 3 | 67 | | 24 | 6 | 3 | 67 | | 32 | 8 | 3 | 67 | | 28 | 7 | 3 | 67 | | 48 | 12 | 3 | 43 | | 44 | 11 | 3 | 43 | | 40 | 10 | 3 | 43 | | 21 | 5 | 4 | 100 | | 17 | 4 | 4 | 100 | | 25 | 6 | 4 | 100 | | 9 | 2 | 4 | 99 | | 13 | 3 | 4 | 99 | | 29 | 7 | 4 | 88 | | 33 | 8 | 4 | 88 | | 41 | 10 | 4 | 87 | | 49 | 12 | 4 | 87 | | 45 | 11 | 4 | 87 | | 5 | 1 | 4 | 66 | | 37 | 9 | 4 | 22 | +-----+------------+-----------+-----+ #表1：求出每門課程的課程course_id,與最高分數first_num SELECT course_id,max(num) first_num FROM score GROUP BY course_id; +-----------+-----------+ | course_id | first_num | +-----------+-----------+ | 1 | 91 | | 2 | 100 | | 3 | 87 | | 4 | 100 | +-----------+-----------+ #表2：去掉最高分，再按照課程分組，取得的最高分，就是第二高的分數second_num SELECT score.course_id,max(num) second_num FROM score INNER JOIN ( SELECT course_id,max(num) first_num FROM score GROUP BY course_id) AS t ON score.course_id = t.course_id WHERE score.num < t.first_num GROUP BY course_id; +-----------+------------+ | course_id | second_num | +-----------+------------+ | 1 | 90 | | 2 | 88 | | 3 | 68 | | 4 | 99 | +-----------+------------+ #將表1和表2聯合到一起，得到一張表t3，包含課程course_id與該們課程的first_num與second_num SELECT t1.course_id,t1.first_num,t2.second_num FROM (SELECT course_id, max(num) first_num FROM score GROUP BY course_id) AS t1 INNER JOIN ( SELECT score.course_id,max(num) second_num FROM score INNER JOIN ( SELECT course_id,max(num) first_num FROM score GROUP BY course_id) AS t ON score.course_id = t.course_id WHERE score.num < t.first_num GROUP BY course_id ) AS t2 ON t1.course_id = t2.course_id; +-----------+-----------+------------+ | course_id | first_num | second_num | +-----------+-----------+------------+ | 1 | 91 | 90 | | 2 | 100 | 88 | | 3 | 87 | 68 | | 4 | 100 | 99 | +-----------+-----------+------------+ #查詢前兩名的學生（有可能出現并列第一或者并列第二的情況） SELECT score.student_id,t3.course_id,t3.first_num,t3.second_num FROM score INNER JOIN ( SELECT t1.course_id,t1.first_num,t2.second_num FROM ( SELECT course_id,max(num) first_num FROM score GROUP BY course_id) AS t1 INNER JOIN ( SELECT score.course_id,max(num) second_num FROM score INNER JOIN (SELECT course_id, max(num) first_num FROM score GROUP BY course_id) AS t ON score.course_id = t.course_id WHERE score.num < t.first_num GROUP BY course_id) AS t2 ON t1.course_id = t2.course_id ) AS t3 ON score.course_id = t3.course_id WHERE score.num >= t3.second_num AND score.num <= t3.first_num; +------------+-----------+-----------+------------+ | student_id | course_id | first_num | second_num | +------------+-----------+-----------+------------+ | 2 | 3 | 87 | 68 | | 2 | 4 | 100 | 99 | | 3 | 3 | 87 | 68 | | 3 | 4 | 100 | 99 | | 4 | 4 | 100 | 99 | | 5 | 4 | 100 | 99 | | 6 | 2 | 100 | 88 | | 6 | 4 | 100 | 99 | | 7 | 2 | 100 | 88 | | 8 | 2 | 100 | 88 | | 9 | 1 | 91 | 90 | | 9 | 2 | 100 | 88 | | 10 | 1 | 91 | 90 | | 11 | 1 | 91 | 90 | | 12 | 1 | 91 | 90 | | 13 | 3 | 87 | 68 | +------------+-----------+-----------+------------+ #排序后可以看的明顯點 SELECT score.student_id,t3.course_id,t3.first_num,t3.second_num FROM score INNER JOIN ( SELECT t1.course_id,t1.first_num,t2.second_num FROM ( SELECT course_id,max(num) first_num FROM score GROUP BY course_id) AS t1 INNER JOIN ( SELECT score.course_id,max(num) second_num FROM score INNER JOIN (SELECT course_id,max(num) first_num FROM score GROUP BY course_id) AS t ON score.course_id = t.course_id WHERE score.num < t.first_num GROUP BY course_id) AS t2 ON t1.course_id = t2.course_id ) AS t3 ON score.course_id = t3.course_id WHERE score.num >= t3.second_num AND score.num <= t3.first_num ORDER BY course_id; +------------+-----------+-----------+------------+ | student_id | course_id | first_num | second_num | +------------+-----------+-----------+------------+ | 9 | 1 | 91 | 90 | | 10 | 1 | 91 | 90 | | 11 | 1 | 91 | 90 | | 12 | 1 | 91 | 90 | | 8 | 2 | 100 | 88 | | 9 | 2 | 100 | 88 | | 6 | 2 | 100 | 88 | | 7 | 2 | 100 | 88 | | 2 | 3 | 87 | 68 | | 3 | 3 | 87 | 68 | | 13 | 3 | 87 | 68 | | 2 | 4 | 100 | 99 | | 3 | 4 | 100 | 99 | | 4 | 4 | 100 | 99 | | 5 | 4 | 100 | 99 | | 6 | 4 | 100 | 99 | +------------+-----------+-----------+------------+
21、查詢不同課程但成績相同的學號，課程號，成績
select distinct t1.student_id,t1.course_id,t1.num from score t1,(select student_id,course_id, num from score) t2 where t1.num=t2.num and t1.course_id <>t2.course_id order by num; +------------+-----------+-----+ | student_id | course_id | num | +------------+-----------+-----+ | 6 | 1 | 9 | | 7 | 1 | 9 | | 8 | 1 | 9 | | 1 | 2 | 9 | | 1 | 4 | 66 | | 3 | 2 | 66 | | 12 | 2 | 77 | | 10 | 2 | 77 | | 3 | 1 | 77 | | 11 | 2 | 77 | | 3 | 3 | 87 | | 11 | 4 | 87 | | 12 | 4 | 87 | | 13 | 3 | 87 | | 10 | 4 | 87 | | 7 | 4 | 88 | | 8 | 4 | 88 | | 9 | 2 | 88 | | 4 | 4 | 100 | | 5 | 4 | 100 | | 6 | 2 | 100 | | 6 | 4 | 100 | | 7 | 2 | 100 | | 8 | 2 | 100 | +------------+-----------+-----+
22、查詢沒學過“葉平”老師課程的學生姓名以及選修的課程名稱；
SELECT student.sname,course.cname FROM student,course WHERE sid NOT IN ( SELECT DISTINCT student_id FROM score WHERE course_id IN ( SELECT course.cid FROM course INNER JOIN teacher ON course.teacher_id = teacher.tid WHERE teacher.tname = '葉平老師' )); +--------+--------+ | sname | cname | +--------+--------+ | 理解 | 生物 | | 理解 | 物理 | | 理解 | 體育 | | 理解 | 美術 | | 鋼蛋 | 生物 | | 鋼蛋 | 物理 | | 鋼蛋 | 體育 | | 鋼蛋 | 美術 | | 張三 | 生物 | | 張三 | 物理 | | 張三 | 體育 | | 張三 | 美術 | | 張一 | 生物 | | 張一 | 物理 | | 張一 | 體育 | | 張一 | 美術 | | 張二 | 生物 | | 張二 | 物理 | | 張二 | 體育 | | 張二 | 美術 | | 張四 | 生物 | | 張四 | 物理 | | 張四 | 體育 | | 張四 | 美術 | | 鐵錘 | 生物 | | 鐵錘 | 物理 | | 鐵錘 | 體育 | | 鐵錘 | 美術 | | 李三 | 生物 | | 李三 | 物理 | | 李三 | 體育 | | 李三 | 美術 | | 李一 | 生物 | | 李一 | 物理 | | 李一 | 體育 | | 李一 | 美術 | | 李二 | 生物 | | 李二 | 物理 | | 李二 | 體育 | | 李二 | 美術 | | 李四 | 生物 | | 李四 | 物理 | | 李四 | 體育 | | 李四 | 美術 | | 如花 | 生物 | | 如花 | 物理 | | 如花 | 體育 | | 如花 | 美術 | | 劉三 | 生物 | | 劉三 | 物理 | | 劉三 | 體育 | | 劉三 | 美術 | | 劉一 | 生物 | | 劉一 | 物理 | | 劉一 | 體育 | | 劉一 | 美術 | | 劉二 | 生物 | | 劉二 | 物理 | | 劉二 | 體育 | | 劉二 | 美術 | | 劉四 | 生物 | | 劉四 | 物理 | | 劉四 | 體育 | | 劉四 | 美術 | +--------+--------+
23、查詢所有選修了學號為1的同學選修過的一門或者多門課程的同學學號和姓名；
SELECT sid,sname FROM student WHERE sid in (SELECT DISTINCT student_id FROM score WHERE course_id in (SELECT course_id FROM score WHERE student_id=1)); +-----+--------+ | sid | sname | +-----+--------+ | 1 | 理解 | | 2 | 鋼蛋 | | 3 | 張三 | | 4 | 張一 | | 5 | 張二 | | 6 | 張四 | | 7 | 鐵錘 | | 8 | 李三 | | 9 | 李一 | | 10 | 李二 | | 11 | 李四 | | 12 | 如花 | +-----+--------+
24、任課最多的老師中學生單科成績最高的學生姓名
SELECT sname FROM student WHERE sid IN (SELECT student_id FROM score,(SELECT course_id,MAX(num) 最大值 FROM score WHERE course_id in (SELECT cid FROM course WHERE teacher_id=(SELECT teacher_id FROM course GROUP BY teacher_id ORDER BY COUNT(cid) DESC LIMIT 1)) GROUP BY course_id HAVING max(num)) A WHERE A.最大值=score.num AND score.course_id=A.course_id); +--------+ | sname | +--------+ | 張一 | | 張二 | | 張四 | | 鐵錘 | | 李三 | +--------+
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