MySQL 触发器将列设置为 max + 1 不起作用

Question

我在为一组用户 ID 编写将排名列设置为最大排名值加 1 的触发器时遇到了困难。也许代码会比我的描述更有帮助:

CREATE TABLE `saved_listing` (
  `saved_listing_id` int(10) NOT NULL auto_increment,
  `user_id` int(10) NOT NULL default '0',
  `listing_id` int(10) NOT NULL default '0',
  `listing_ty` varchar(10) NOT NULL default '',
  `notes` text NULL,
  `rank` int(10) NOT NULL default '0',
  `modify_by` int(10) NOT NULL default '1',
  `modify_dt` timestamp NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  `create_by` int(10) NOT NULL default '1',
  `create_dt` datetime NOT NULL default '0000-00-00 00:00:00',
  `active` enum('Yes','No') NOT NULL default 'No',
  PRIMARY KEY  (`saved_listing_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=0 ;

这是我的触发代码:

CREATE TRIGGER ins_saved_listing BEFORE INSERT ON saved_listing
FOR EACH ROW BEGIN
    SET NEW.create_dt = NOW();
    SET NEW.rank = (SELECT MAX(rank) + 1 FROM saved_listing WHERE user_id = NEW.user_id);
END

这是我收到的错误消息:

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 '' at line 3

如有任何帮助，我们将不胜感激。我没有太多编写触发器的经验。

MySQL服务器版本:5.1.49-3~bpo50+1

Answer 1

那是因为mysql看到了;(分隔符)，中断了CREATE TRIGGER的执行

试着改成:

delimiter |


CREATE TRIGGER ins_saved_listing BEFORE INSERT ON saved_listing
FOR EACH ROW BEGIN
    SET NEW.create_dt = NOW();
    SET NEW.rank = (SELECT MAX(rank) + 1 FROM saved_listing WHERE user_id = NEW.user_id);
END;

|

delimiter ;