Mysql GROUP_CONCAT 根據計數相乘

Question

我正在嘗試進行一個 mysql 查詢，即 GROUP_CONCAT 是表 'shop_previews' 中的所有字符串。 但是，當運行以下查詢時，它會根據“timesBought”的數量重復它。

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 等於 2，並且 shop_previews.image 中只有一個結果，則它會將該條目與自身連接起來，從而產生類似

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