Question

我能够实现我的结果的唯一方法是创造一些在我眼中非常难看的东西，处理查询需要很长时间但却无法提出更简单的方法：

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了DESC LIMIT 1，确保只选择了最新的应用程序......所有这些都在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，其最新名称的iDeviant应用程序应该是该组顶部的应用程序：

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');

Answer 1

你尝试过这个：

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：

因为我们在每个组中按created排序，所以我们从此列开始，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。我认为我们不会在最近的将来有时间戳＆gt; 15位数，所以我们是安全的
CONCAT与name。将name放在连接的右侧。这是为了以后SUBSTRING来自此连接
按此升序（MIN）进行排序，因此我们将有效地按created
ASC GROUP BY applications.identifier, applications.platform进行排序>
现在我们拥有最早的created以及每组pplications.identifier，applications.platform

name

SUBSTRING连接的信息，得到两个部分1-15（created）和16个结尾（name），将它们选为两个不同的列

如何从需要订购的分组表中选择多个值

1 个答案: