在MySQL中使用條件更新記錄

Question

我有以下查詢

SELECT count(Distinct user_bookmarks.user_id) AS bookmark_counter, bookmark_id 
FROM user_bookmarks 
LEFT JOIN bookmarks ON user_bookmarks.bookmark_id = bookmarks.id 
group by user_bookmarks.bookmark_id

很好

現在我想更新書簽表中的記錄

UPDATE bookmark 
set bookmarks_counter = bookmark_counter from from above query 
where id = bookmark_id which is again from above query

從上面查詢

任何想法？

我們可以做到嗎？

謝謝

Answer 1

您可以像這樣在更新中編寫查詢

UPDATE bookmark bk,
(   SELECT count(Distinct user_bookmarks.user_id) AS bookmark_counter, bookmark_id 
    FROM user_bookmarks 
    LEFT JOIN bookmarks ON user_bookmarks.bookmark_id = bookmarks.id 
    GROUP BY user_bookmarks.bookmark_id
) t
SET bk.bookmarks_counter = t.bookmark_counter
WHERE bk.id = t.bookmark_id

Answer 2

您可以嘗試以下方法：

UPDATE dbo.bookmarks SET bookmarks_counter = result 
WHERE user_bookmarks.user_id 
IN (SELECT count(Distinct user_bookmarks.user_id)
    AS bookmark_counter, bookmark_id  FROM user_bookmarks 
    LEFT JOIN bookmarks ON user_bookmarks.bookmark_id =  bookmarks.id  
    GROUP BY user_bookmarks.bookmark_id)

Answer 3

試試這個：

 UPDATE
   bookmark 
SET 
   bookmark.bookmarks_counter = other.bookmark_counter 

FROM
    (SELECT count(Distinct user_bookmarks.user_id) AS bookmark_counter, bookmark_id 
FROM user_bookmarks 
LEFT JOIN bookmarks ON user_bookmarks.bookmark_id = bookmarks.id 
group by user_bookmarks.bookmark_id) other
WHERE 
   bookmark.id = other.bookmark_id