一個引用字段對多個外鍵約束的可能用途

Question

我想要制作3張這樣的桌子：

wc_groups表

CREATE TABLE IF NOT EXISTS `wc_groups` (
  `id` int(2) unsigned NOT NULL AUTO_INCREMENT,
  `idgroup` int(7) NOT NULL,
  `title` varchar(10) NOT NULL,
  `content` text,
  `status` smallint(1) NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`),
  UNIQUE KEY `idgroup` (`idgroup`),
  KEY `status` (`status`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

wc_matches表

CREATE TABLE IF NOT EXISTS `wc_matches` (
  `id` int(4) unsigned NOT NULL AUTO_INCREMENT,
  `time` date NOT NULL,
  `group_id` int(2) unsigned NOT NULL,
  `place` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
  `team_id_1` int(10) unsigned NOT NULL,
  `team_id_2` int(10) unsigned NOT NULL,
  `edituser` varchar(50) COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`id`),
  KEY `group_id_foreign` (`group_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1 ;

wc_teams表

CREATE TABLE IF NOT EXISTS `wc_teams` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  `group_id` int(2) unsigned NOT NULL,
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1 ;

ALTER TABLE `wc_teams`
  ADD CONSTRAINT `group_id_foreign` FOREIGN KEY (`group_id`) REFERENCES `wc_groups` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;

為什么執行代碼創建表wc_team時出現錯誤？

可以使用什么？可以使用一個引用字段（ wc_groups （ id ））對多個外鍵約束進行使用？

Answer 1

我不明白您對多個外鍵的意思。

但是在wc_teams create查詢中的問題是您迷路了

 `group_id` int(2) unsigned NOT NULL,

但是你也錯過了主鍵，所以我想你需要這個

CREATE TABLE IF NOT EXISTS `wc_teams` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
  `group_id` int(2) unsigned NOT NULL,
   PRIMARY KEY (`id`)
 ) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1 ;