#1241-操作数应包含1列 [英] #1241 - Operand should contain 1 column(s)

问题描述

在以下查询中，我试图为每个类别获取一张图片

In the following query am trying to get one image per category

SELECT  l.*
FROM    (
   SELECT  id AS category_id,
           COALESCE(
           (
           SELECT  *
           FROM    images li
           WHERE li.category_id = dlo.id

           ORDER BY
                       li.save_status DESC, li.category_id DESC, li.id DESC
           LIMIT 1
           ), 0) AS mid
   FROM    cats_imgs dlo where id='1'
   ) lo
JOIN    images l
ON      l.save_status = '3'
   AND l.category_id >= lo.category_id
   AND l.category_id <= lo.category_id
   AND l.id >= lo.mid

但继续出现以下错误:

#1241 - Operand should contain 1 column(s)

有什么想法吗?

推荐答案

用images li

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