MySQL：不同的行为取决于结果的位置

我正在修改一个现有的项目。我想将3个mysql请求分组在一个组中

这3个请求具有相同的选定数据，仅在其中更改。 下面是一个请求示例：

SELECT COUNT(seg.my_seg1) FROM (
SELECT COUNT(DISTINCT cp.conference_id) as my_seg1 FROM A.Account a
INNER JOIN A.ConferenceParticipant cp ON a.account_id = cp.user_id
INNER JOIN A.Conference cf ON cf.id = cp.conference_id
WHERE cf.`status` = 0
AND DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= cf.creation_timestamp
GROUP BY a.account_id) as seg
WHERE seg.my_seg1 >= 30

---

因此，我的问题是，如何根据同一请求中的WHERE结果获得3个不同的值？

像这样，您将有3个虚拟列：

SELECT 
    COUNT(IF(seg.my_seg1 >= 30, 1, 0)) AS res1,
    COUNT(IF(seg.my_seg1 >= 11 AND seg.my_seg1 < 30, 1, 0)) AS res2
FROM (
    SELECT COUNT(DISTINCT cp.conference_id) as my_seg1 
    FROM A.Account a
            JOIN A.ConferenceParticipant cp ON a.account_id = cp.user_id
            JOIN A.Conference cf ON cf.id = cp.conference_id
    WHERE 
        cf.`status` = 0
    AND DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= cf.creation_timestamp
    GROUP BY a.account_id
) AS seg

---

但是你必须修改你的过滤器，你说的是3个，但我只看到2个不同的。

这正是我需要的，谢谢。事实上，只有2个，复制/粘贴失败。还没试过，但看起来很完美。好吧，我编辑了。另外，我将上限改为<30，而不是原来的想法。再次感谢。

WHERE seg.my_seg1 >= 30;

SELECT 
    COUNT(IF(seg.my_seg1 >= 30, 1, 0)) AS res1,
    COUNT(IF(seg.my_seg1 >= 11 AND seg.my_seg1 < 30, 1, 0)) AS res2
FROM (
    SELECT COUNT(DISTINCT cp.conference_id) as my_seg1 
    FROM A.Account a
            JOIN A.ConferenceParticipant cp ON a.account_id = cp.user_id
            JOIN A.Conference cf ON cf.id = cp.conference_id
    WHERE 
        cf.`status` = 0
    AND DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= cf.creation_timestamp
    GROUP BY a.account_id
) AS seg