/*
一对一
*/
CREATE TABLE teacher(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(20)
);
CREATE TABLE student(
id INT PRIMARY KEY AUTO_INCREMENT,
s_name VARCHAR(20),
t_id INT UNIQUE,
CONSTRAINT wj_001 FOREIGN KEY (t_id) REFERENCES teacher(id)
);
/*
多对多
*/
CREATE TABLE t1(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(20)
);
CREATE TABLE s1(
id INT PRIMARY KEY AUTO_INCREMENT,
s_name VARCHAR(20)
);
CREATE TABLE a(
s_id INT,
t_id INT,
CONSTRAINT wj_002 FOREIGN KEY (t_id) REFERENCES t1(id),
CONSTRAINT wj_003 FOREIGN KEY (s_id) REFERENCES s2(id)
);
/*
一对多
*/
CREATE TABLE t(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(20)
);
CREATE TABLE s(
id INT PRIMARY KEY AUTO_INCREMENT,
s_name VARCHAR(20),
t_id INT,
CONSTRAINT wj_004 FOREIGN KEY (t_id) REFERENCES t(id)
);