我想把COUNT(item_id)
放在这条语句中:
SELECT * FROM `notifications` WHERE `uid` = '3' AND `seen` = '0' AND id IN (
SELECT MAX(id), COUNT(item_id)
FROM `notifications`
GROUP BY item_id
) ORDER BY id DESC
但出现此错误:操作数应包含1列。
表:
[id] [uid] [item_id] [seen]
1 3 69 0
2 3 69 0
3 3 70 0
4 3 69 0
5 3 70 0
6 3 69 0
预期输出:(按id排序),其中69是最后一条记录。
[item_id] [num]
69 4
70 2
https://stackoverflow.com/questions/50767573
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