这个 MAX() GROUP BY 查询有什么问题？

Question

我正在努力获取一个查询来显示具有不同类别的民意调查中得票最多的选项。目标是获取 site_polls_votes 中出现次数最多的 vote_id，并将其按 site_polls 中的 cat_id 分组，以便在 site_polls_cat 中仅显示每个类别的投票最多的值，即 9。

然而，奇怪的是，查询没有从 site_polls 返回正确的数据，而是返回我不希望返回的数据。

这是 DDL...

CREATE TABLE IF NOT EXISTS `site_polls` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `cat_id` int(11) NOT NULL,
  `value` varchar(255) NOT NULL,
  `icon_url` varchar(255) DEFAULT NULL,
  `radio_id` int(11) NOT NULL,
  `status` enum('0','1') NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`),
  KEY `fs_id` (`radio_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=75 ;

INSERT INTO `site_polls` (`id`, `cat_id`, `value`, `icon_url`, `radio_id`, `status`) VALUES
(1, 1, 'Navvid', 'hd.png', 1, '1'),
(2, 1, 'NavvoNight', 'f13c3b96c52ae8bd69a1202f703f9ba0.png', 2, '1'),
(3, 1, 'ProNavvo', '39fd904f5510a2a9e5a75892e54ffc4b.png', 3, '1'),
(4, 1, 'IceNavvo', '9488c40ba45ed8175e61cdc684701d98.png', 5, '1'),
(5, 1, 'Navvoz', '627165967747d031cbca7d31d778400e.png', 9, '1'),
(6, 1, 'Navvlindados', 'ff3f8a271623a9bd34f15af2b9766fe3.png', 12, '1'),
(7, 1, 'BeatsNavvo', '71b789e9dd822d4e86ee76a74917cb6c.png', 14, '1'),
(8, 2, 'Arequis.', NULL, 5, '1'),
(9, 2, '.Hiroshima', NULL, 5, '1'),
(10, 2, 'Lyferhd', NULL, 5, '1'),
(11, 2, 'Cold.-.', NULL, 5, '1'),
(12, 2, 'Styamban', NULL, 5, '1'),
(13, 3, 'Lyps', NULL, 5, '1'),
(14, 3, 'bolaudozinho', NULL, 5, '1'),
(15, 3, 'Sr.Donatella', NULL, 5, '1'),
(16, 3, ':Stefanie0103', NULL, 5, '1'),
(17, 3, 'X-DesconhecidoX', NULL, 5, '1'),
(18, 4, 'wilsNavvoz', NULL, 5, '1'),
(19, 4, 'Incapaciidade', NULL, 5, '1'),
(20, 4, 'bruno64681', NULL, 5, '1'),
(21, 4, '=O=Marlon=O=', NULL, 5, '1'),
(22, 4, '-lordzika-', NULL, 5, '1'),
(23, 5, 'Incapaciidade', NULL, 5, '1'),
(24, 5, 'Lyferhd', NULL, 5, '1'),
(25, 5, 'wilsNavvoz', NULL, 5, '1'),
(26, 5, 'bolaudozinho', NULL, 5, '1'),
(27, 5, 'Dj.samuel.....', NULL, 5, '1'),
(28, 6, 'bruno64681', NULL, 5, '1'),
(29, 6, 'Incapaciidade', NULL, 5, '1'),
(30, 6, '.:Mariio:.', NULL, 5, '1'),
(31, 6, 'l.modric10', NULL, 5, '1'),
(32, 7, 'Lyps', NULL, 5, '1'),
(33, 7, 'Incapaciidade', NULL, 5, '1'),
(34, 7, '.:Mariio:.', NULL, 5, '1'),
(35, 7, '-lordzika-', NULL, 5, '1'),
(36, 7, 'SuperGrandChase2', NULL, 5, '1'),
(37, 8, '.:SurfistAa:.', NULL, 5, '1'),
(38, 8, 'Nelpsbreaker', NULL, 5, '1'),
(39, 8, 'Lyps', NULL, 5, '1'),
(40, 2, 'guilherme58512', NULL, 14, '1'),
(41, 2, 'erick.BAN10', NULL, 14, '1'),
(42, 2, 'Srto.GeetNavvo', NULL, 14, '1'),
(43, 2, 'Fients', NULL, 14, '1'),
(44, 3, 'HannahMello', NULL, 14, '1'),
(45, 3, 'DjAtualizado', NULL, 14, '1'),
(46, 3, '-TheusAlves.Ban', NULL, 14, '1'),
(47, 3, 'Pokadork', NULL, 14, '1'),
(48, 3, 'Dockepand', NULL, 14, '1'),
(49, 4, 'mavsonhc', NULL, 14, '1'),
(50, 4, 'TheMatencio', NULL, 14, '1'),
(51, 4, 'Dioguiiitoo', NULL, 14, '1'),
(52, 4, ',MatheuSinho10', NULL, 14, '1'),
(53, 5, 'Deboxadooanjo', NULL, 14, '1'),
(54, 5, 'Loranny.:', '', 14, '1'),
(55, 5, 'luizfernan4', NULL, 14, '1'),
(56, 5, 'lucasvoa', NULL, 14, '1'),
(57, 5, '--Djdana09--', NULL, 14, '1'),
(58, 6, 'luidygomesf', NULL, 14, '1'),
(59, 6, 'Domgabriel12365', NULL, 14, '1'),
(60, 6, 'Tac@-Fogo', NULL, 14, '1'),
(61, 6, 'stephanyeclub', NULL, 14, '1'),
(62, 6, 'Ops.Luuh', NULL, 14, '1'),
(63, 7, 'Dioguiiitoo', NULL, 14, '1'),
(64, 7, ',Yakaha', NULL, 14, '1'),
(65, 7, 'Dockepand', NULL, 14, '1'),
(66, 7, 'HannahMello', NULL, 14, '1'),
(67, 8, 'iDescreto', NULL, 5, '1'),
(68, 8, 'KevinK.CRS', NULL, 14, '1'),
(69, 8, 'samusan45', NULL, 14, '1'),
(70, 8, 'HannahMello', NULL, 14, '1'),
(71, 8, 'L3G4CY', NULL, 14, '1'),
(72, 9, '.Misteriow', NULL, 14, '1'),
(73, 9, 'Piresmobi2', NULL, 14, '1'),
(74, 9, 'Nadson.Oculto', NULL, 14, '1');

CREATE TABLE IF NOT EXISTS `site_polls_cat` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) NOT NULL,
  `icon` enum('0','1') NOT NULL DEFAULT '0',
  `status` enum('0','1') NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=10 ;

INSERT INTO `site_polls_cat` (`id`, `title`, `icon`, `status`) VALUES
(1, 'Radio', '1', '1'),
(2, 'Webmaster', '0', '1'),
(3, 'Admini', '0', '1'),
(4, 'Coord', '0', '1'),
(5, 'Dj', '0', '1'),
(6, 'Moderator', '0', '1'),
(7, 'Press', '0', '1'),
(8, 'Promoter', '0', '1'),
(9, 'Artist', '0', '1');

CREATE TABLE IF NOT EXISTS `site_polls_votes` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `vote_id` int(11) NOT NULL,
  `data` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `vote_id` (`vote_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=10 ;

INSERT INTO `site_polls_votes` (`id`, `user_id`, `vote_id`, `data`) VALUES
(1, 2961, 2, 1481698602),
(2, 923, 2, 1481698679),
(3, 174, 5, 1481705971),
(4, 174, 8, 1481748108),
(5, 174, 15, 1481748132),
(6, 174, 22, 1481748153),
(7, 174, 36, 1481748188),
(8, 2961, 8, 1481794986),
(9, 2961, 45, 1481803289);

CREATE TABLE IF NOT EXISTS `site_radios` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `ip` varchar(255) NOT NULL,
  `icon` varchar(255) NOT NULL,
  `color` varchar(255) NOT NULL,
  `status` enum('0','1') NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=18 ;

INSERT INTO `site_radios` (`id`, `name`, `ip`, `icon`, `color`, `status`) VALUES
(1, 'Navvid', '', 'Navvid.png', '#1777BC', '1'),
(2, 'NavvoNight', '', 'NavvoNight.png', '#3F1028', '1'),
(3, 'ProNavvo', '', 'ProNavvo.png', '#79BEDF', '1'),
(4, 'Pixelados', '', 'Pixelados.png', '#F0CA24', '0'),
(5, 'IceNavvo', '', 'IceNavvo.png', '#28ADFF', '1'),
(6, 'Navvonautas', '', 'Navvonautas.png', '#607391', '0'),
(7, 'Navvonados', '', 'Navvonados.png', '#93D4FF', '0'),
(8, 'KiNavvo', '', 'KiNavvo.png', '#308F95', '0'),
(9, 'Navvoz', '', 'Navvoz.png', '#C96547', '1'),
(10, 'Navvoleiros', '', 'Navvoleiros.png', '#8AC206', '0'),
(11, 'HBFM', '', '../dfff358a8030a4314ba1b0988a7251d4.png', '#0962BB', '0'),
(12, 'Navvlindados', '', '../58e2b864131ec83c84dca257c13874d0.png', '#F4BD49', '1'),
(13, 'ColdNavvo', '', '../66e217354c04a3d909ccd3c0efd20f8a.png', '#3A9BD1', '0'),
(14, 'BeatsNavvo', '', '../c28f753683e959c512e9ff7bf659635b.png', '#66B7DB', '1'),
(15, 'Nobba', '', '../c7029ca90687bc4a531fd780599eb085.png', '#FFCC4D', '0'),
(16, 'ConectionFM', '', '../537b5ae135bc7fc17d37991fbf40ec40.png', '#E44549', '1'),
(17, 'NavvoColor', '', '../88106d7614c550bdd9014e0d5948a3ab.png', '#D20052', '1');

我已在 SQLFiddle 中重现了该问题，请单击 here。

如果 SQLFiddle 不适合您，这里是查询：

SELECT MAX(t.totalvotes) AS votes,
   t.value,
   t.cat_id,
   t.radio_id,
   t.icon_url,
   t.title,
   t.icon_radio
FROM
  (SELECT COALESCE(COUNT(DISTINCT(v.id)),0) AS totalvotes,
      e.value,
      e.cat_id,
      e.radio_id,
      e.icon_url,
      c.title,
      r.icon AS icon_radio
  FROM site_polls_votes v
  LEFT OUTER JOIN site_polls e ON e.id = v.vote_id
  INNER JOIN site_polls_cat c ON e.cat_id = c.id
  INNER JOIN site_radios r ON e.radio_id = r.id
  GROUP BY e.cat_id) t
GROUP BY t.cat_id
ORDER BY rand()

结果：

期望的结果应该是 2 票投给“NavvoNight”，1 票投给“DjAtualizado”。我认为问题在于查询将 cat_id 的所有投票相加并将其归因于获胜者，使其仍然是得票最多的，但根据 site_polls_votes 显示错误的票数。

还希望：如果没有人对特定类别投票，它也显示 0 票，因此查询将始终根据类别数量显示结果数量，就像我之前所说的那样，是 9。我已经设法让这个“有点”工作，但显示绝对错误的获胜者，将 LEFT OUTER JOIN 部分更改为 RIGHT OUTER JOIN。请看这里：

任何帮助将不胜感激，提前致谢！

Answer 1

从头开始

试试这个：

select
IF(a.totalvotes > 0, a.totalvotes, 0) as totalvotes,
IF(a.totalvotes > 0,b.value, c.value),
IF(a.totalvotes > 0,b.cat_id, c.cat_id),
IF(a.totalvotes > 0,b.radio_id, c.radio_id),
IF(a.totalvotes > 0,b.icon_url, c.icon_url),
a.title
from

(select e.id, count(distinct(v.id)) as totalvotes, e.title
from
site_polls_cat as e
left join site_polls as s ON (e.id = s.cat_id)
left join site_polls_votes as v ON (s.id = v.vote_id)
group by e.title ) as a

left join
(select s.id, s.value, s.cat_id, s.radio_id, s.icon_url, count(distinct(v.id)) as sitevotes
from
(site_polls as s, site_polls_votes as v)
left join site_radios as r ON (s.radio_id = r.id)
where
s.id = v.vote_id
group by
s.id, s.cat_id
order by sitevotes DESC) as b on (a.id = b.cat_id)

left join
(select s.id, s.value, s.cat_id, s.radio_id, s.icon_url
from
(site_polls as s, site_polls_cat as e)
left join site_polls_votes as v on (s.id = v.vote_id)
where
s.cat_id = e.id
&& v.vote_id is null
group by
s.cat_id, s.id
order by
RAND()) as c on (a.id = c.cat_id)

group by
a.id
order by RAND()

会产生这样的结果：