mysql - 使用 MySQL 选择最后 5 个条目的 SUM 的最大值？

Question

嘿，我不是 MySQL 的最大专家，但这是我到目前为止获得 MAX 入口的东西

   SELECT DISTINCT 
          websites.id, 
          websites.title, 
          websites.url, 
          websites.screenshot, 
          impressions.number, 
          blocks.price 
     FROM websites 
LEFT JOIN blocks ON websites.id = blocks.website 
LEFT JOIN impressions ON blocks.id = impressions.block 
    WHERE status = 1 
      AND blocks.active = '1' 
      AND impressions.number = (SELECT MAX(number) 
                                  FROM impressions)

我想做的是选择最大(数字)但最后 5 个条目的总和。我试过乱搞，但就是搞不定。

Answer 1

最后五次印象。这个应该做的数字虽然不知道你想总结什么

SELECT DISTINCT websites.id, 
                websites.title, 
                websites.url, 
                websites.screenshot, 
                impressions.number, 
                blocks.price 
FROM   websites 
       LEFT JOIN blocks 
         ON websites.id = blocks.website 
       LEFT JOIN impressions 
         ON blocks.id = impressions.block 
WHERE  status = 1 
       AND blocks.active = '1' 
ORDER  BY impressions.number 
LIMIT  5 

如果你想对 blocks.price 求和，你可以这样做

 SELECT SUM(lastblocks.price) 
   FROM (
    SELECT 
          price
    FROM   websites 
           LEFT JOIN blocks 
             ON websites.id = blocks.website 
           LEFT JOIN impressions 
             ON blocks.id = impressions.block 
    WHERE  status = 1 
           AND blocks.active = '1' 
    ORDER  BY impressions.number 
    LIMIT  5 ) lastblocks