Mysql GROUP_CONCAT 基于计数相乘

Question

我正在尝试对 GROUP_CONCAT 表“shop_previews”中的所有字符串进行 mysql 查询。 但是，在运行以下查询时，它会根据“timesBought”的数量重复它。

select 
    `shop_items`.*, 
     group_concat(shop_previews.image) as images, 
     count(`shop_histories`.`shopId`) as `timesBought` 
from `shop_items`
left join `shop_previews` on `shop_previews`.`shopId` = `shop_items`.`id`
left join `shop_histories` on `shop_items`.`id` = `shop_histories`.`shopId`
group by `shop_items`.`id` 
order by `timesBought` desc

因此，如果 timesBought 等于 2，并且 shop_previews.image 中只有一个结果，它将将该条目与自身连接起来，从而产生类似

https://example.com/example.png,https://example.com/example.png

Answer 1

GROUP_CONCAT()支持DISTINCT：

GROUP_CONCAT(DISTINCT shop_previews.image) as images