创建“用户”和“朋友”关系

Question

我有两张桌子：

_________          ____________
| users |          | friends  |
|_______|          |__________|
| id    |          | id_user1 |
| nick  |          | id_user2 |
|_______|          |__________|

但如果我尝试加入，就像

一样

Alter table friends add Foreign Key (id_user1) references users (id) on delete  restrict on update  restrict;
Alter table friends add Foreign Key (id_user2) references users (id) on delete  restrict on update  restrict;

我收到Identical attribute name "id" in entity "friends" 错误。我该怎么做？

Answer 1

这对我有用：

CREATE TABLE users (id INT NOT NULL PRIMARY KEY) ENGINE=InnoDB;
CREATE TABLE friends (id_user1 INT NOT NULL, id_user2 INT NOT NULL) ENGINE=InnoDB;
Alter table friends add Foreign Key (id_user1) references users (id) on delete  restrict on update  restrict;
Alter table friends add Foreign Key (id_user2) references users (id) on delete  restrict on update  restrict;