mysql - 尝试修改 MySQL 中的表时出错

Question

我正在尝试向表中添加一列并将其设为外键，但我不断收到此错误:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FOREIGN KEY(idplayer) REFERENCES players(playersid)' at line 1

下面是我在更改语句之前的代码:

CREATE TABLE transactions 
  ( 
     transid  INT UNSIGNED NOT NULL AUTO_INCREMENT, 
     type     VARCHAR(20), 
     fromteam VARCHAR(30), 
     toteam   VARCHAR(30), 
     idplayer INT UNSIGNED NOT NULL, 
     PRIMARY KEY(transid) 
  ); 

现在我尝试更改 idplayer 并将其设为外键:

ALTER TABLE transactions
MODIFY idplayer INT UNSIGNED NOT NULL
FOREIGN KEY(idplayer) REFERENCES players(playersid)

请提供帮助。

Answer 1

首先，您在NOT NULL后面缺少一个逗号，其次您需要告诉mysql添加CONSTRAINT。尝试一下:

ALTER TABLE `events`
MODIFY idplayer INT UNSIGNED NOT NULL,
ADD CONSTRAINT `FK_Name` FOREIGN KEY (idplayer) REFERENCES players(playersid);