小背景:我已经花了大半天的时间来研究这个问题,我很兴奋我几乎找到了解决方案,只是我似乎无法将最终的 MySQL 查询放在一起。这都是关于MySQL语法的,所以我相信不需要给出表模式等。
查询部分:
1)
SELECT id, globalId, date, serverId, gamemodeId, mapId FROM levelsloaded
2)
(
(SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
FROM playerjoins WHERE playerId = 2224 AND date <= levelsloaded.date
ORDER BY date DESC)
UNION ALL
(SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
FROM playerleaves WHERE playerId = 2224 AND date <= levelsloaded.date
ORDER BY date DESC)
ORDER BY date DESC LIMIT 1) below
3)
(
(SELECT id, globalId, date, serverId, playerId, 'playerjoins' AS origin
FROM playerjoins WHERE playerId = 2224 AND date >= levelsloaded.date
ORDER BY date ASC)
UNION ALL
(SELECT id, globalId, date, serverId, playerId, 'playerleaves' AS origin
FROM playerleaves WHERE playerId = 2224 AND date >= levelsloaded.date
ORDER BY date ASC)
ORDER BY date ASC LIMIT 1) above
如果需要的话,这里是架构:
CREATE TABLE `levelsloaded` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`globalId` int(11) NOT NULL,
`date` datetime NOT NULL,
`serverId` int(11) NOT NULL,
`gamemodeId` int(11) NOT NULL,
`mapId` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `globalId` (`globalId`),
KEY `date` (`date`),
KEY `serverId` (`serverId`),
KEY `gamemodeId` (`gamemodeId`),
KEY `mapId` (`mapId`),
CONSTRAINT `levelsloaded_ibfk_1` FOREIGN KEY (`serverId`) REFERENCES `servers` (`serverId`),
CONSTRAINT `levelsloaded_ibfk_2` FOREIGN KEY (`gamemodeId`) REFERENCES `gamemodes` (`gamemodeId`),
CONSTRAINT `levelsloaded_ibfk_3` FOREIGN KEY (`mapId`) REFERENCES `maps` (`mapId`)
) ENGINE=InnoDB AUTO_INCREMENT=1104 DEFAULT CHARSET=latin1
<小时/>
CREATE TABLE `playerjoins` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`globalId` int(11) NOT NULL,
`date` datetime NOT NULL,
`serverId` int(11) NOT NULL,
`playerId` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `globalId` (`globalId`),
KEY `date` (`date`),
KEY `serverId` (`serverId`),
KEY `playerId` (`playerId`),
CONSTRAINT `playerjoins_ibfk_1` FOREIGN KEY (`serverId`) REFERENCES `servers` (`serverId`),
CONSTRAINT `playerjoins_ibfk_2` FOREIGN KEY (`playerId`) REFERENCES `players` (`playerId`)
) ENGINE=InnoDB AUTO_INCREMENT=64983 DEFAULT CHARSET=latin1
<小时/>
CREATE TABLE `playerleaves` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`globalId` int(11) NOT NULL,
`date` datetime NOT NULL,
`serverId` int(11) NOT NULL,
`playerId` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `globalId` (`globalId`),
KEY `date` (`date`),
KEY `serverId` (`serverId`),
KEY `playerId` (`playerId`),
CONSTRAINT `playerleaves_ibfk_1` FOREIGN KEY (`serverId`) REFERENCES `servers` (`serverId`),
CONSTRAINT `playerleaves_ibfk_2` FOREIGN KEY (`playerId`) REFERENCES `players` (`playerId`)
) ENGINE=InnoDB AUTO_INCREMENT=45676 DEFAULT CHARSET=latin1
现在回答问题:
我想将查询部分 (1) 与部分 (2) 和 (3) 结合起来,只有在 below.origin = ' 时才会返回
。我目前陷入了合并表格和 IF 部分的困境。levelsloaded
中的行playerjoin' AND above.origin = 'playerleave'
最佳答案
尽管这不是最有效的方法。
SELECT id, globalId, date, serverId, gamemodeId, mapId
FROM levelsloaded l
JOIN above a ON 1 = 1
JOIN below b ON 1 = 1
WHERE b.origin = 'playerjoin' AND a.origin = 'playerleave'
关于mysql - 从三个简单查询创建复杂查询,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20225472/