MySQLの外部キー制約RESTRICT,CASCADE,SET NULL,NO ACTIONの違いは？ - Qiita-- Create syntax for TABLE 'categories' CREATE TABLE `categories` ( `id` int(11) unsigned NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; -- Create syntax for TABLE 'items' CREATE TABLE `items` ( `id` int(11) unsigned NOT NULL, `category_id` int(11) unsigned NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Object#freezeについて - Qiita
