mysql - 添加外键时在 "REFERENCES"附近出现错误 #1064

Question

我在尝试创建外键时不断收到错误 1064:

ALTER TABLE `zajimavost`
    ADD CONSTRAINT FK_zaj_bod 
    FOREIGN KEY def_bod
      REFERENCES `bod`(`gid`)
      ON UPDATE CASCADE ON DELETE CASCADE;

它提示:

#1064 - 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 'REFERENCES `bod`(`gid`)
      ON UPDATE CASCADE ON DELETE CASCADE' at line 4

不管有没有反引号我都试过了，问题总是一样的。

我的表:

CREATE TABLE `zajimavost` (
 `zaj_id` int(11) NOT NULL,
 `lok_id` int(11) NOT NULL,
 `nazev` varchar(255) COLLATE utf8_czech_ci NOT NULL,
 `kategorie` int(11) NOT NULL DEFAULT '1',
 `datace_od` int(11) NOT NULL DEFAULT '31',
 `datace_do` int(11) NOT NULL DEFAULT '60',
 `def_bod` int(11) DEFAULT NULL,
 PRIMARY KEY (`zaj_id`),
 KEY `ck_zaj_lok` (`lok_id`),
 KEY `zaj_id` (`zaj_id`),
 KEY `FK_zaj_kat` (`kategorie`),
 KEY `FK_zaj_bod` (`def_bod`),
 CONSTRAINT `FK_zaj_kat` FOREIGN KEY (`kategorie`) REFERENCES `kategorie` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
 CONSTRAINT `fk_zaj_lok` FOREIGN KEY (`lok_id`) REFERENCES `lokalita` (`lok_id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_czech_ci

CREATE TABLE `bod` (
 `gid` int(11) NOT NULL AUTO_INCREMENT,
 `geom` point DEFAULT NULL,
 `radius` int(4) NOT NULL DEFAULT '50',
 PRIMARY KEY (`gid`)
) ENGINE=InnoDB AUTO_INCREMENT=30 DEFAULT CHARSET=utf8 COLLATE=utf8_czech_ci

表中有数据。

那么怎么解决呢？

Answer 1

添加外键时需要在子表列名中使用()，试试这个

ALTER TABLE zajimavost 
ADD CONSTRAINT FK_zaj_bod 
FOREIGN KEY (def_bod) REFERENCES `bod`(`gid`)  
ON UPDATE CASCADE ON DELETE CASCADE;