据我所知，如果我错了，请纠正我，一个班级有一个老师，简化，一个老师教一个或多个班级（更复杂的情况是每个班级不止一个老师）：关系是1对多，所以班级表应该包含一个教师id
一个学生可以上多个班，但是一个班有很多学生，那么关系是多对多的，应该为每个学生创建一个新的表
当然，我们需要用相关信息填充它们，
一旦完成，我们就可以连接所有相关的表并得到时间表
添加教师id列：

ALTER TABLE class ADD COLUMN teacher_id INT(9) NOT NULL;
ALTER TABLE class ADD KEY teacher_id (teacher_id);

创建多对多表

CREATE TABLE class_per_student (
 id INT(11) NOT NULL AUTO_INCREMENT,
 class_id INT(9) NOT NULL,
 student_id INT(9) NOT NULL,
 PRIMARY KEY id (id),
 KEY class_id (class_id),
 KEY student_id (student_id)
);

时间表选择：

SELECT
 cps.class_id,
 cps.student_id,
 c.teacher_id
FROM
 class_per_student cps
 INNER JOIN class c ON c.id = cps.class_d
;

请注意，由于所有实体之间的关系都是多对多的，因此每个实体（class、teacher、student）都会出现多次，但这3个实体的唯一组合只会出现一次

创建如下表：，

create table subject(subject_id int primary key,sub_name varchar(20))
 create table teacher(teacher_id int primary key,teacher_name varchar(20))
 create table class(class_id int primary key,class_sec varchar(20))

 create table timetable(t_id int primary key,subject_id int references 
 subject(subject_id)
 ,teacher_id int references teacher(teacher_id),class_id int references 
 class(class_id))

插入样本值

insert into subject values(1,'Tamil')
 insert into teacher values(1,'Pugal')
 insert into class values(1,'12th A')
 insert into timetable values(1,1,1,1)

使用内部连接连接表，

select s.sub_name,t.teacher_name,c.class_sec from timetable t1 
 inner join subject s
 on s.subject_id = t1.subject_id inner join teacher t
 on t.teacher_id = t1.teacher_id inner join class c
 on c.class_id   = t1.class_id

试试这个…如果需要任何澄清，请回复我。。

SELECT Teachers.teacher_name, Class.class_sec, Subjects.subject_name FROM timetable
INNER JOIN Teachers ON Teachers.teacher_id = timetable.teacher_id
INNER JOIN Class ON Class.class_id = timetable.class_id
INNER JOIN Subjects ON Subjects.subject_id = timetable.subject_id