Question

我想在INSERT上创建一个MySQL触发器：当在wp_posts表中插入新记录时，我想更新wp_posts.post_author从其他两个表中检索数据，使用两个子查询（我想这可以做得更好）。

无论如何，更新应该是＆＃34;条件＆＃34;，即只有当wp_posts.post_title值为＆＃34; A＆＃34;，＆＃34; B＆＃34时才必须更新行;或＆＃34; C＆＃34;。这可能吗？

这就是我的尝试：

CREATE TRIGGER updatePostIDonInsert
AFTER INSERT
   ON wp_posts FOR EACH ROW

BEGIN

   -- variable declarations

   -- trigger code
// ? (pseudo: if wp_posts.post_title IN ("A","B","C") then...)

UPDATE wp_posts SET post_author = 
(SELECT ID from wp_users WHERE user_email = 
(SELECT meta_value FROM `wp_postmeta` WHERE post_id = wp_posts.ID AND meta_key = "_from_email"))

END;

感谢任何帮助

[更新]我尝试的最新查询：

CREATE TRIGGER updatePostIDonInsert
    BEFORE INSERT
       ON wp_posts FOR EACH ROW
    BEGIN

    IF FIND_IN_SET(NEW.post_title,'General contact,Website contact,Master contact') > 0 AND NEW.post_type ='inbound_com' THEN
    SET NEW.post_author = (SELECT ID from wp_users WHERE user_email = (SELECT meta_value FROM wp_postmeta WHERE post_id = NEW.ID AND meta_key = '_from_email'));

    END IF;

    END;

（如果通过PhpMyAdmin触发部分插入，但没有最终的END并从IF开始，则此方法有效）

Answer 1

像这样的东西。而不是触发AFTER INSERT利用BEFORE INSERT TRIGGER

    CREATE TRIGGER updatePostIDonInsert
    BEFORE INSERT
       ON wp_posts FOR EACH ROW
    BEGIN
        // add this condition    
    IF FIND_IN_SET(NEW.post_title,'A,B,C') > 0 THEN

            -- variable declarations

            -- trigger code
            SET NEW.post_author = (SELECT ID from wp_users WHERE user_email =
(SELECT meta_value FROM `wp_postmeta` WHERE post_id = NEW.ID AND meta_key = "_from_email") LIMIT 1);
        END IF;

    END;

您需要确保在子查询中只返回一行。我不熟悉您的数据库结构，因此我无法真正告诉您如何优化post_author的子查询。

剩下的由你决定。您可以随时使用FIND_IN_SET。

Answer 2

这是你需要的吗？

此处触发器只会在新插入的post_title（“A”，“B”，“C”）中执行某些操作

CREATE TRIGGER updatePostIDonInsert
AFTER INSERT
   ON wp_posts FOR EACH ROW
BEGIN
    // add this condition
    IF (NEW.post_title IN ("A","B","C")) THEN

        -- variable declarations

        -- trigger code
        // ? (pseudo: if wp_posts.post_title IN ("A","B","C") then...)

        UPDATE wp_posts SET post_author = 
        (SELECT ID from wp_users WHERE user_email = 
        (SELECT meta_value FROM `wp_postmeta` WHERE post_id = wp_posts.ID AND meta_key = "_from_email"))
    END IF;

END;

MySQL触发器和条件更新

2 个答案: