我有一个名为“排名”的表，我需要来自联盟数据库的各种信息。 我创建了单个查询，但我想帮助合并到一两个查询中。
我的活动表：
id int(11)
event_id int(11)
player_id int(11)
tournament_id int(11)
location_id int(11)
standing varchar(10)
amount int(11)
created datetime
SELECT COUNT(*) AS FirstPlaceStandings FROM standings WHERE player_id = 31 AND standing = 1
SELECT SUM(amount) AS FirstPlaceEarnings FROM standings WHERE player_id = 31 AND standing = 1
SELECT COUNT(*) AS SecondPlaceStandings FROM standings WHERE player_id = 31 AND standing = 2
SELECT SUM(amount) AS SecondPlaceEarnings FROM standings WHERE player_id = 31 AND standing = 2
SELECT COUNT(*) AS ThirdPlaceStandings FROM standings WHERE player_id = 31 AND standing = 3
SELECT SUM(amount) AS ThirdPlaceEarnings FROM standings WHERE player_id = 31 AND standing = 3
SELECT COUNT(*) AS TotalPlaces FROM standings WHERE player_id = 31
SELECT SUM(amount) AS TotalEarnings FROM standings WHERE player_id = 31
这是我的样本数据：
CREATE TABLE IF NOT EXISTS `standings` (
`id` int(11) NOT NULL,
`event_id` int(11) NOT NULL,
`player_id` int(11) NOT NULL,
`tournament_id` int(11) NOT NULL,
`location_id` int(11) NOT NULL,
`standing` varchar(10) NOT NULL,
`amount` int(11) NOT NULL,
`created` datetime NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=49 ;
--
-- Dumping data for table `standings`
--
INSERT INTO `standings` (`id`, `event_id`, `player_id`, `tournament_id`, `location_id`, `standing`, `amount`, `created`) VALUES
(7, 8, 32, 14, 12, '1', 101, '2015-11-22 12:52:07'),
(8, 8, 31, 14, 12, '2', 60, '2015-11-22 12:52:07'),
(9, 8, 27, 14, 12, '3', 30, '2015-11-22 12:52:07'),
(10, 9, 30, 18, 16, '1', 150, '2015-11-22 14:45:11'),
(11, 9, 32, 18, 16, '2', 95, '2015-11-22 14:45:11'),
(12, 9, 27, 18, 16, '3', 40, '2015-11-22 14:45:11'),
(13, 10, 26, 14, 12, '1', 155, '2015-11-22 14:46:22'),
(14, 10, 28, 14, 12, '2', 97, '2015-11-22 14:46:22'),
(15, 10, 32, 14, 12, '3', 45, '2015-11-22 14:46:22'),
(19, 12, 31, 18, 16, '1', 100, '2015-11-22 16:03:50'),
(20, 12, 27, 18, 16, '2', 60, '2015-11-22 16:03:50'),
(21, 12, 30, 18, 16, '3', 20, '2015-11-22 16:03:50'),
(22, 13, 27, 8, 2, '1', 108, '2015-11-22 16:20:13'),
(23, 13, 31, 8, 2, '2', 67, '2015-11-22 16:20:13'),
(24, 13, 29, 8, 2, '3', 27, '2015-11-22 16:20:13'),
(25, 14, 31, 14, 14, '1', 500, '2015-11-27 20:22:17'),
(26, 14, 26, 14, 12, '2', 250, '2015-11-27 20:22:17'),
(27, 14, 29, 14, 12, '3', 125, '2015-11-27 20:22:17'),
(28, 15, 27, 38, 2, '1', 376, '2015-11-27 20:23:44'),
(29, 15, 28, 38, 2, '2', 200, '2015-11-27 20:23:44'),
(30, 15, 30, 38, 2, '3', 160, '2015-11-27 20:23:44'),
(34, 17, 32, 19, 18, '1', 100, '2015-11-28 21:46:45'),
(35, 17, 27, 19, 18, '2', 50, '2015-11-28 21:46:45'),
(36, 17, 26, 19, 18, '3', 25, '2015-11-28 21:46:45'),
(37, 18, 27, 14, 12, '1', 200, '2015-11-28 21:48:57'),
(38, 18, 26, 14, 12, '2', 100, '2015-11-28 21:48:57'),
(39, 18, 31, 14, 12, '3', 50, '2015-11-28 21:48:57'),
(40, 19, 26, 23, 19, '1', 250, '2015-11-28 21:50:09'),
(41, 19, 34, 23, 19, '2', 125, '2015-11-28 21:50:09'),
(42, 19, 33, 23, 19, '3', 76, '2015-11-28 21:50:09'),
(43, 20, 26, 23, 19, '1', 250, '2015-11-28 21:50:32'),
(44, 20, 34, 23, 19, '2', 125, '2015-11-28 21:50:32'),
(45, 20, 33, 23, 19, '3', 75, '2015-11-28 21:50:32'),
(46, 21, 33, 18, 16, '1', 500, '2015-11-28 21:56:37'),
(47, 21, 35, 18, 16, '2', 250, '2015-11-28 21:56:37'),
(48, 21, 29, 18, 16, '3', 125, '2015-11-28 21:56:37');
答案 0 :(得分：1)
这两个查询可以合并：
SELECT COUNT(*) AS TotalPlaces, SUM(amount) AS TotalEarnings
FROM standings
WHERE player_id = 31
最后使用CASE和小hack（转换COUNT - ＆gt; SUM（CASE WHEN ...那么1 ELSE 0 END））：
SELECT COUNT(*) AS TotalPlaces, SUM(amount) AS TotalEarnings,
SUM(CASE WHEN standing = 1 THEN 1 ELSE 0 END) AS FirstPlaceStandings,
SUM(CASE WHEN standing = 1 THEN amount ELSE 0 END) AS FirstPlaceEarnings,
SUM(CASE WHEN standing = 2 THEN 1 ELSE 0 END) AS SecondPlaceStandings,
SUM(CASE WHEN standing = 2 THEN amount ELSE 0 END) AS SecondPlaceEarnings,
SUM(CASE WHEN standing = 3 THEN 1 ELSE 0 END) AS ThirdPlaceStandings,
SUM(CASE WHEN standing = 3 THEN amount ELSE 0 END) AS ThirdPlaceEarnings
FROM standings
WHERE player_id = 31