Question

我遇到了MySql的问题，我尝试为表写入触发器，但我的知识几乎没有。我想做的事？当有人把某些东西放在表B中时，我想要更新表A中的一些记录。但是为了做到这一点，我首先需要从表B中计算值为1和-1的行。这是我的3桌

CREATE TABLE IF NOT EXISTS `wp_comment_vote` (
  `vote_id` int(11) NOT NULL AUTO_INCREMENT,
  `comment_id` int(11) NOT NULL,
  `user_id` int(11) NOT NULL,
  `value` int(11) NOT NULL,
  `meta_id` int(11) NOT NULL,
  `date` date NOT NULL,
  PRIMARY KEY (`vote_id`)
)

CREATE TABLE IF NOT EXISTS `wp_comments` (
  `comment_ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `comment_post_ID` bigint(20) unsigned NOT NULL DEFAULT '0',,
  `user_id` bigint(20) unsigned NOT NULL DEFAULT '0'
  `comment_author` tinytext NOT NULL,
  `comment_author_email` varchar(100) NOT NULL DEFAULT '',
  `comment_author_url` varchar(200) NOT NULL DEFAULT '',
  `comment_author_IP` varchar(100) NOT NULL DEFAULT '',
  `comment_date` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `comment_date_gmt` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `comment_content` text NOT NULLN',
  PRIMARY KEY (`comment_ID`)
)



CREATE TABLE IF NOT EXISTS `wp_commentmeta` (
  `meta_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `comment_id` bigint(20) unsigned NOT NULL DEFAULT '0',
  `meta_key` varchar(255) DEFAULT NULL,
  `meta_value` longtext,
  PRIMARY KEY (`meta_id`),
  KEY `comment_id` (`comment_id`),
  KEY `meta_key` (`meta_key`)
)

delimiter //
CREATE TRIGGER countvotecomment AFTER UPDATE ON wp_comment_vote
FOR EACH ROW BEGIN
UPDATE wp_commentmeta
IF wp_commentmeta.meta_key = 'vote_comment_in_minus' THAN
SET wp_commentmeta.meta_value = (SELECT COUNT( value ) as glosy FROM wp_comment_vote WHERE comment_id=wp_commentmeta.comment_id AND value = '-1');
ELSEIF wp_commentmeta.meta_key = 'vote_comment_in_plus' THAN
SET wp_commentmeta.meta_value = (SELECT COUNT( value ) as glosy FROM wp_comment_vote WHERE comment_id=wp_commentmeta.comment_id AND value = '1') 
END;
delimiter ;

Answer 1

触发器应如下所示：

CREATE TRIGGER votecomment 
AFTER INSERT ON wp_comment_vote 
FOR EACH ROW 
BEGIN 
UPDATE wp_commentmeta SET meta_value = (SELECT COUNT(value) FROM `wp_comment_vote` WHERE comment_id = NEW.comment_id AND value = 1) WHERE meta_key = 'vote_comment_in_plus'; 
END;$$

它不是以100％结尾，因为我需要为vote_comment_in_minus添加第二个UPDATE，但它有效！

如何为3个表构建触发器

1 个答案: