如何从需要排序的分组表中选择多个值答案

【问题标题】：How can I select multiple values from a grouped table that need to be under order如何从需要排序的分组表中选择多个值
【发布时间】：2013-11-20 21:03:17
【问题描述】：

我能够实现我的结果的唯一方法是创建一些在我看来非常丑陋的东西，处理查询需要很长时间，但无法想出更简单的东西：

SELECT 
*, COUNT(Application.id) AS count, 
(SELECT id FROM applications WHERE identifier = Application.identifier AND platform = Application.platform ORDER BY created DESC LIMIT 1) AS id, 
(SELECT location FROM applications WHERE identifier = Application.identifier AND platform = Application.platform ORDER BY created DESC LIMIT 1) AS location, 
(SELECT name FROM applications WHERE identifier = Application.identifier AND platform = Application.platform ORDER BY created DESC LIMIT 1) AS name, 
(SELECT version FROM applications WHERE identifier = Application.identifier AND platform = Application.platform ORDER BY created DESC LIMIT 1) AS version, 
(SELECT created FROM applications WHERE identifier = Application.identifier AND platform = Application.platform ORDER BY created DESC LIMIT 1) AS created 
FROM `enterpriseappstore`.`applications` AS `Application` 
WHERE 1 = 1 
GROUP BY `Application`.`identifier`, `Application`.`platform` 
ORDER BY `Application`.`name` ASC, `Application`.`created` DESC

请注意 ORDER BY 在每个子查询中创建的 DESC LIMIT 1 确保只选择了最新的应用程序......一切都在 cakePHP 项目中（如 97）： https://github.com/Ridiculous-Innovations/EnterpriseAppStore/blob/master/web/app/Model/Application.php

供您参考，有一个表格和一些示例数据，名称中带有Latest的iDeviant应用程序应该是组顶部的那个：

CREATE TABLE `applications` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  `identifier` varchar(150) NOT NULL,
  `url` varchar(255) NOT NULL,
  `platform` tinyint(2) unsigned NOT NULL,
  `version` varchar(15) NOT NULL,
  `size` bigint(20) unsigned NOT NULL DEFAULT '0',
  `sort` int(5) unsigned NOT NULL DEFAULT '1000',
  `config` text NOT NULL,
  `location` tinyint(2) unsigned NOT NULL DEFAULT '0',
  `created` datetime NOT NULL,
  `modified` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `name` (`name`,`identifier`,`platform`,`sort`),
  KEY `version` (`version`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;

--
-- Dumping data for table `applications`
--

INSERT INTO `applications` (`id`, `name`, `identifier`, `url`, `platform`, `version`, `size`, `sort`, `config`, `location`, `created`, `modified`) VALUES
(1, 'iDeviant', 'com.fuerteint.iDeviant', '', 1, '4.0', 1059404, 1000, '{"plist":{"CFBundleDisplayName":"iDeviant","CFBundleName":"iDeviant","DTXcode":"0501","DTSDKName":"iphoneos7.0","UISupportedInterfaceOrientations~ipad":["UIInterfaceOrientationPortrait","UIInterfaceOrientationPortraitUpsideDown","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"CFBundleIcons~ipad":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60","AppIcon76x76"]}},"DTSDKBuild":"11B508","CFBundleDevelopmentRegion":"en","CFBundleVersion":"1.0","BuildMachineOSBuild":"13A603","DTPlatformName":"iphoneos","CFBundleShortVersionString":"4.0","CFBundlePackageType":"APPL","CFBundleSupportedPlatforms":["iPhoneOS"],"CFBundleInfoDictionaryVersion":"6.0","UIRequiredDeviceCapabilities":["armv7"],"DTCompiler":"com.apple.compilers.llvm.clang.1_0","CFBundleExecutable":"iDeviant","UILaunchImages":[{"UILaunchImageOrientation":"Portrait","UILaunchImageName":"LaunchImage-700-568h","UILaunchImageSize":"{320, 568}","UILaunchImageMinimumOSVersion":"7.0"}],"CFBundleResourceSpecification":"ResourceRules.plist","MinimumOSVersion":"7.0","UIDeviceFamily":[1],"UIViewControllerBasedStatusBarAppearance":false,"DTXcodeBuild":"5A2053","CFBundleIdentifier":"com.fuerteint.iDeviant","UIAppFonts":["FontAwesome.ttf"],"CFBundleSignature":"????","DTPlatformVersion":"7.0","CFBundleIcons":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60"]}},"LSRequiresIPhoneOS":true,"UISupportedInterfaceOrientations":["UIInterfaceOrientationPortrait","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"DTPlatformBuild":"11B508"},"icons":["AppIcon29x29@2x.png","AppIcon29x29@2x~ipad.png","AppIcon29x29~ipad.png","AppIcon40x40@2x.png","AppIcon40x40@2x~ipad.png","AppIcon40x40~ipad.png","AppIcon60x60@2x.png","AppIcon76x76@2x~ipad.png","AppIcon76x76~ipad.png"],"provisioning":"enterprise","author":"","description":"","fullDescription":""}', 1, '2013-11-19 14:36:01', '2013-11-19 14:36:01'),
(29, 'removeya-debug', 'cz.ursimon.removya', '', 3, '1.0', 536699, 1000, '{"version-code":"1","install-location":"0","min-sdk-version":"8","screen-sizes":{"anydensity":"true","smallscreens":"true","normalscreens":"true","largescreens":"true","resizeable":"true"},"permissions":[],"author":"","description":"","fullDescription":""}', 0, '2013-11-20 09:40:35', '2013-11-20 09:40:35'),
(30, 'iDeviant', 'com.fuerteint.iDeviant', '', 1, '4.0', 1059404, 1000, '{"plist":{"CFBundleDisplayName":"iDeviant","CFBundleName":"iDeviant","DTXcode":"0501","DTSDKName":"iphoneos7.0","UISupportedInterfaceOrientations~ipad":["UIInterfaceOrientationPortrait","UIInterfaceOrientationPortraitUpsideDown","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"CFBundleIcons~ipad":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60","AppIcon76x76"]}},"DTSDKBuild":"11B508","CFBundleDevelopmentRegion":"en","CFBundleVersion":"1.0","BuildMachineOSBuild":"13A603","DTPlatformName":"iphoneos","CFBundleShortVersionString":"4.0","CFBundlePackageType":"APPL","CFBundleSupportedPlatforms":["iPhoneOS"],"CFBundleInfoDictionaryVersion":"6.0","UIRequiredDeviceCapabilities":["armv7"],"DTCompiler":"com.apple.compilers.llvm.clang.1_0","CFBundleExecutable":"iDeviant","UILaunchImages":[{"UILaunchImageOrientation":"Portrait","UILaunchImageName":"LaunchImage-700-568h","UILaunchImageSize":"{320, 568}","UILaunchImageMinimumOSVersion":"7.0"}],"CFBundleResourceSpecification":"ResourceRules.plist","MinimumOSVersion":"7.0","UIDeviceFamily":[1],"UIViewControllerBasedStatusBarAppearance":false,"DTXcodeBuild":"5A2053","CFBundleIdentifier":"com.fuerteint.iDeviant","UIAppFonts":["FontAwesome.ttf"],"CFBundleSignature":"????","DTPlatformVersion":"7.0","CFBundleIcons":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60"]}},"LSRequiresIPhoneOS":true,"UISupportedInterfaceOrientations":["UIInterfaceOrientationPortrait","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"DTPlatformBuild":"11B508"},"icons":["AppIcon29x29@2x.png","AppIcon29x29@2x~ipad.png","AppIcon29x29~ipad.png","AppIcon40x40@2x.png","AppIcon40x40@2x~ipad.png","AppIcon40x40~ipad.png","AppIcon60x60@2x.png","AppIcon76x76@2x~ipad.png","AppIcon76x76~ipad.png"],"provisioning":"enterprise"}', 0, '2013-11-20 21:08:09', '2013-11-20 21:08:09'),
(31, 'iDeviant', 'com.fuerteint.iDeviant', '', 1, '4.0', 1059404, 1000, '{"plist":{"CFBundleDisplayName":"iDeviant","CFBundleName":"iDeviant","DTXcode":"0501","DTSDKName":"iphoneos7.0","UISupportedInterfaceOrientations~ipad":["UIInterfaceOrientationPortrait","UIInterfaceOrientationPortraitUpsideDown","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"CFBundleIcons~ipad":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60","AppIcon76x76"]}},"DTSDKBuild":"11B508","CFBundleDevelopmentRegion":"en","CFBundleVersion":"1.0","BuildMachineOSBuild":"13A603","DTPlatformName":"iphoneos","CFBundleShortVersionString":"4.0","CFBundlePackageType":"APPL","CFBundleSupportedPlatforms":["iPhoneOS"],"CFBundleInfoDictionaryVersion":"6.0","UIRequiredDeviceCapabilities":["armv7"],"DTCompiler":"com.apple.compilers.llvm.clang.1_0","CFBundleExecutable":"iDeviant","UILaunchImages":[{"UILaunchImageOrientation":"Portrait","UILaunchImageName":"LaunchImage-700-568h","UILaunchImageSize":"{320, 568}","UILaunchImageMinimumOSVersion":"7.0"}],"CFBundleResourceSpecification":"ResourceRules.plist","MinimumOSVersion":"7.0","UIDeviceFamily":[1],"UIViewControllerBasedStatusBarAppearance":false,"DTXcodeBuild":"5A2053","CFBundleIdentifier":"com.fuerteint.iDeviant","UIAppFonts":["FontAwesome.ttf"],"CFBundleSignature":"????","DTPlatformVersion":"7.0","CFBundleIcons":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60"]}},"LSRequiresIPhoneOS":true,"UISupportedInterfaceOrientations":["UIInterfaceOrientationPortrait","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"DTPlatformBuild":"11B508"},"icons":["AppIcon29x29@2x.png","AppIcon29x29@2x~ipad.png","AppIcon29x29~ipad.png","AppIcon40x40@2x.png","AppIcon40x40@2x~ipad.png","AppIcon40x40~ipad.png","AppIcon60x60@2x.png","AppIcon76x76@2x~ipad.png","AppIcon76x76~ipad.png"],"provisioning":"enterprise"}', 0, '2013-11-20 21:08:22', '2013-11-20 21:08:22'),
(32, 'iDeviant Latest', 'com.fuerteint.iDeviant', '', 1, '5.0', 1059404, 1000, '{"plist":{"CFBundleDisplayName":"iDeviant","CFBundleName":"iDeviant","DTXcode":"0501","DTSDKName":"iphoneos7.0","UISupportedInterfaceOrientations~ipad":["UIInterfaceOrientationPortrait","UIInterfaceOrientationPortraitUpsideDown","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"CFBundleIcons~ipad":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60","AppIcon76x76"]}},"DTSDKBuild":"11B508","CFBundleDevelopmentRegion":"en","CFBundleVersion":"1.0","BuildMachineOSBuild":"13A603","DTPlatformName":"iphoneos","CFBundleShortVersionString":"4.0","CFBundlePackageType":"APPL","CFBundleSupportedPlatforms":["iPhoneOS"],"CFBundleInfoDictionaryVersion":"6.0","UIRequiredDeviceCapabilities":["armv7"],"DTCompiler":"com.apple.compilers.llvm.clang.1_0","CFBundleExecutable":"iDeviant","UILaunchImages":[{"UILaunchImageOrientation":"Portrait","UILaunchImageName":"LaunchImage-700-568h","UILaunchImageSize":"{320, 568}","UILaunchImageMinimumOSVersion":"7.0"}],"CFBundleResourceSpecification":"ResourceRules.plist","MinimumOSVersion":"7.0","UIDeviceFamily":[1],"UIViewControllerBasedStatusBarAppearance":false,"DTXcodeBuild":"5A2053","CFBundleIdentifier":"com.fuerteint.iDeviant","UIAppFonts":["FontAwesome.ttf"],"CFBundleSignature":"????","DTPlatformVersion":"7.0","CFBundleIcons":{"CFBundlePrimaryIcon":{"CFBundleIconFiles":["AppIcon29x29","AppIcon40x40","AppIcon60x60"]}},"LSRequiresIPhoneOS":true,"UISupportedInterfaceOrientations":["UIInterfaceOrientationPortrait","UIInterfaceOrientationLandscapeLeft","UIInterfaceOrientationLandscapeRight"],"DTPlatformBuild":"11B508"},"icons":["AppIcon29x29@2x.png","AppIcon29x29@2x~ipad.png","AppIcon29x29~ipad.png","AppIcon40x40@2x.png","AppIcon40x40@2x~ipad.png","AppIcon40x40~ipad.png","AppIcon60x60@2x.png","AppIcon76x76@2x~ipad.png","AppIcon76x76~ipad.png"],"provisioning":"enterprise"}', 0, '2013-11-20 21:08:35', '2013-11-20 21:08:35');

【问题讨论】：

标签： php mysql sql cakephp

【解决方案1】：

你试过这个吗：

SELECT FROM_UNIXTIME(SUBSTR(MIN(CONCAT(LPAD(UNIX_TIMESTAMP(`created`),15,'0'),`name`)),1,15)) AS `date`,
SUBSTR(MIN(CONCAT(LPAD(UNIX_TIMESTAMP(`created`),15,'0'),`name`)),16) AS `name` 
FROM `applications`
GROUP BY `applications`.`identifier`, `applications`.`platform`;

这个想法是：

由于我们在每个组中按created 排序，因此我们从该列开始，将其转换为时间戳。 UNIX_TIMESTAMP(created)
在左边用零填充到固定长度，比如 15。我认为我们在最近的将来不会有 >15 位的时间戳，所以我们是安全的
CONCAT 它与name。将name 放在串联的右侧。这是为了以后SUBSTRING'ing 从这个串联中得到它
按此串联升序排序（MIN），因此我们将在GROUP BY applications.identifier, applications.platform 组内按created ASC 进行有效排序
现在我们有最早的created 以及右侧的name 有价值的信息，用于每组pplications.identifier、applications.platform
SUBSTRING拼接后的信息，得到1-15（created）和16-end（name）两部分，分别选为两个不同的列

【讨论】：

不幸的是，这仍然会从示例表中返回 id=1 的行:(
所以您需要的不是最早的，而是created 的最新记录？如果是这样，您可以在我的查询中将 MIN 更改为 MAX 并尝试吗？