mysql - 可以将这 2 个 SQL 查询更改为 1 个吗？

Question

是否可以将这 2 个查询更改为 1 个？

查询 #1：

UPDATE  `pvdownloader`.`posts`
SET  `exists` =  'y'
WHERE source = ANY (SELECT source FROM dbdownloader.posts)
  AND `mangacount` = 0
  AND NOT `exists` = 'm'

查询 #2：

UPDATE `pvdownloader`.`posts`
SET  `exists` =  'n'
WHERE `exists` = 'u'
  AND `mangacount` = 0

我假设可以用 IF/ELSE 制作这样的东西，但我根本不知道如何使用它：<

Answer 1

也许这样的事情会起作用：

update
  pvdownloader.posts
set
  exists =
    case
      when source = any(select source from dbdownloader.posts) and mangacount = 0 and exists != 'm' then 'y'
      when exists = 'u' and mangacount = 0 then 'n'
    end
where 
  (source = any(select source from dbdownloader.posts) and mangacount = 0 and exists != 'm')
  or
  (exists = 'u' and mangacount = 0)
;

正如@MostyMostacho 所建议的那样，我冒昧地改变了你的逻辑，没有双重否定。