Question

基于具有多个返回值的子选择的MySQL删除语句。

以下是我现在正在做的事情：

DELETE FROM `dnsstats` WHERE id NOT IN
(

 SELECT id FROM
    (
    SELECT id FROM `dnsstats` WHERE peerhost = 'x.x.x.243' ORDER BY id DESC LIMIT 500
    ) foo 
)
 AND id NOT IN
(
 SELECT id FROM
    (
    SELECT id FROM `dnsstats` WHERE peerhost = 'x.x.x.40' ORDER BY id DESC LIMIT 500
  ) foo2
)
 AND id NOT IN
(
 SELECT id FROM
    (
    SELECT id FROM `dnsstats` WHERE peerhost = 'x.x.x.50' ORDER BY id DESC LIMIT 500
  ) foo3
);

这很好用，但我想动态选择各个IP地址：

SELECT peerhost FROM `dnsstats` GROUP BY peerhost;

..并根据返回的值删除。

这是我尝试过的（并且失败了）：

DELETE FROM `dnsstats` WHERE id NOT IN
(
 SELECT id FROM
    (
    SELECT id FROM `dnsstats` WHERE peerhost = (
            SELECT peerhost FROM `dnsstats` GROUP BY peerhost;
        ) ORDER BY id DESC LIMIT 500
    ) foo 
);

知道我能做些什么来使这项工作？谢谢！

Answer 1

我认为您可能需要删除分号 SELECT peerhost FROM dnsstats GROUP BY peerhost;

查询将运行，但我认为您不会得到正确的结果：早些时候，你从每个与peerhost相关的id中得到500，

现在你将获得所有人的500分。您需要更改查询。

==＆GT;编辑：试试这个布莱恩

DELETE FROM dnsstats WHERE id IN
(
    SELECT e.id FROM
    (
        SELECT d.id FROM dnsstats d
        LEFT JOIN
    (
            SELECT a.peerhost,
                (SELECT id FROM dnsstats WHERE peerhost = a.peerhost
                    ORDER BY id DESC LIMIT 499,1) id
            FROM 
            (SELECT peerhost FROM dnsstats GROUP BY peerhost) a
    ) c
    ON d.peerhost = c.peerhost
WHERE d.id < c.id) e);

Answer 2

这就是你想要的？

DELETE FROM `dnsstats` WHERE id NOT IN
(
 SELECT id FROM
    (
    SELECT id FROM `dnsstats` WHERE peerhost in (
            SELECT peerhost FROM `dnsstats` GROUP BY peerhost;
        ) ORDER BY id DESC LIMIT 500
    ) foo 
);

MySQL删除语句基于具有多个返回值的子选择

2 个答案: