SQL 嵌套查询的具体使用（sql 嵌套查询的具体使用什么函数）难以置信

🌐 经济型：买域名、轻量云服务器、用途：游戏网站等《腾讯云》特点：特价机便宜适合初学者用点我优惠购买

🚀 拓展型：买域名、轻量云服务器、用途：游戏网站等《阿里云》特点：中档服务器便宜域名备案事多点我优惠购买

🛡️ 稳定型：买域名、轻量云服务器、用途：游戏网站等《西部数码》特点：比上两家略贵但是稳定性超好事也少点我优惠购买

文章摘要

这篇文章介绍了如何在MySQL数据库中创建和插入数据到多个表中，展示了四个表的结构及其数据关系： 1. **`class` 表**：用于存储班级信息，包括班级ID、班级名称和外键`cid`。2. **`course` 表**：用于存储课程信息，包括课程ID、课程名称、教师ID和外键`cid`。3. **`score` 表**：用于存储学生课程成绩，包括学生成绩ID、学生ID、课程ID、成绩和外键`sid`、`cid`。4. **`student` 表**：用于存储学生信息，包括学生活ID、性别、班级ID和姓名，外键`class_id`关联`class`表。5. **`teacher` 表**：用于存储教师信息，包括教师ID和教师姓名。文章通过`INSERT`语句向这些表中插入了具体的数据，展示了如何将班级、课程、学生和教师信息关联起来，构建了一个完整的学生成绩管理数据库。文章的核心内容是展示如何通过合理设计表的结构和关系，实现对学生、课程和成绩的高效管理。

#创建表及插入记录
CREATE TABLE class (
cid int(11) NOT NULL AUTO_INCREMENT,
caption varchar(32) NOT NULL,
PRIMARY KEY (cid)
) ENGINE=InnoDB CHARSET=utf8;

INSERT INTO class VALUES
(1, ‘三年二班’),
(2, ‘三年三班’),
(3, ‘一年二班’),
(4, ‘二年九班’);

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 DEFAULT CHARSET=utf8;

INSERT INTO course VALUES
(1, ‘生物’, 1),
(2, ‘物理’, 2),
(3, ‘体育’, 3),
(4, ‘美术’, 2);

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 DEFAULT CHARSET=utf8;

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);

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 DEFAULT CHARSET=utf8;

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’)

CREATE TABLE teacher(
tid int(11) NOT NULL AUTO_INCREMENT,
tname varchar(32) NOT NULL,
PRIMARY KEY (tid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

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’);