如果每个对象/项的数字(4)以上,则删除关系

你可以使用:

DELETE FROM Image
WHERE id IN (SELECT sub.id
             FROM (SELECT im.id,
                    ROW_NUMBER() OVER(PARTITION BY i.id ORDER BY im.id) AS rn
                   FROM Item i
                   JOIN Image im
                     ON i.id = im.item_id) sub
             WHERE sub.rn > 4);

在你跑步之前 DELETE 检查子查询是否返回所需的ID。

我会这样做:

delete from image
where id < (select i2.id
            from image i2
            where i2.item_id = i.item_id
            order by id desc
            limit 1 offset 3
           );

这将删除任何 id 比第四大还小 身份证件 对于给定的 item_id .