外部キーの多元ヘルプ！

Question

私は今、2台

TABLE CLASS 
(
    school varchar(50), 
    year varchar(50), 
    grade varchar(50), 
    className varchar(50), 
    PRIMARY KEY (school,year,grade,className) 
) 
TABLE STUDENT 
(
    student_id varchar(50) PRIMARY KEY, 
    detail varchar(50) 
) 

を持って、私は学生のためにサブクラス化します。参照を作成するには？

Answer 1

だけ...

CREATE TABLE CLASS (
    id int not null auto_increment PRIMARY KEY, -- CREATE A KEY COLUMN 
    school varchar(50), 
    year varchar(50), 
    grade varchar(50), 
    className varchar(50), 
    unique (school,year,grade,className) 
); 

CREATE TABLE STUDENT (
    student_id varchar(50) PRIMARY KEY, 
    class_id int references class, -- REFERENCE THE KEY 
    detail varchar(50) 
);