如何更新

Question

我用下面的查詢來更新我的用戶表在MySQL中一個條件的SQL查詢的基地2列

update users set user_likes = 
(CASE WHEN like_by_users NOT LIKE '%user_name%' 
AND dislikes_by_users NOT LIKE '%user_name%' 
THEN (user_likes +1) ELSE user_likes END) 
WHERE post_id = '2221' 

這工作對我很好，但我也想更新likes_by_users這樣

likes_by_users = CONCAT(likes_by_users,' ','user_name') 

我試圖做這樣的

update users set user_likes = 
(CASE WHEN like_by_users NOT LIKE '%user_name%' 
AND dislikes_by_users NOT LIKE '%user_name%' 
THEN (user_likes +1), likes_by_users = CONCAT(likes_by_users,' ','user_name') 
ELSE user_likes END) 
WHERE post_id = '2221' 

不過，這並不在所有的工作。 我不想再次檢查條件，但如果上述條件爲真，那麼它不僅應該更新兩列（user_likes）和（likes_by_users）（user_likes），並且如果條件爲false，那麼它不應該更新任何列。

Answer 1

你可以在WHERE子句的幫助下做到這一點。

UPDATE `users` 
SET `user_likes` = `user_level` + 1, `likes_by_users` = CONCAT(`likes_by_users`, ' ', 'user_name') 
WHERE `post_id` = '2221' 
AND `like_by_users` NOT LIKE '%user_name%' 
AND `dislikes_by_users` NOT LIKE '%user_name%' 

Answer 2

嘗試像這樣

update users 
Set user_likes = IF(like_by_users NOT LIKE '%user_name%' AND dislikes_by_users NOT LIKE '%user_name%',(user_likes + 1), user_likes), 
    likes_by_users = IF(like_by_users NOT LIKE '%user_name%' AND dislikes_by_users NOT LIKE '%user_name%', CONCAT(likes_by_users,' ','user_name'), user_likes) 
WHERE post_id = 2221