编辑代码

CREATE DATABASE test;
use test;
CREATE TABLE S (
	id int,
	name varchar(255),
	address varchar(255),
	city varchar(255)
);
CREATE TABLE C (
    CNO varchar(6) PRIMARY KEY,
    CN varchar(10),
    PC varchar(6),
    FORTEIGN KEY (PC) REFERENCES C(CNO)
);
CREATE TABLE SC (
    SNO varchar(6),
    CNO varchar(6),
    GRADE DEC(4,1),
    PRIMARY KEY (SNO,CNO),
    FORTEIGN KEY (SNO) REFERENCES S(SNO),
    FORTEIGN KEY (CNO) REFERENCES C(CNO),
    CHECK (GRADE BETWEEN 0 AND 100)
)