創造一個 '用戶' 和 '朋友' 關係

Question

我有2個表：

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

但是，如果我嘗試加入他們在一起，像

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; 

我得到一個Identical attribute name "id" in entity "friends"錯誤。我將如何做到這一點？

Answer 1

這個工作對我來說：

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;