[英]i want to use left and inner join in 3 tables in mysql?
these are my tables. 这些是我的桌子。 first one is appusers table.
第一个是appusers表。
CREATE TABLE IF NOT EXISTS `appusers` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`email` varchar(50) NOT NULL,
`is_active` tinyint(2) NOT NULL DEFAULT '0',
`zip` varchar(20) NOT NULL,
`city` text NOT NULL,
`country` text NOT NULL,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=23 ;
second table is stickeruses table. 第二个表是stickeruses表。
CREATE TABLE IF NOT EXISTS `stickeruses` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`sticker_id` int(11) NOT NULL,
`count` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=24 ;
Third table is Devices 第三表是设备
CREATE TABLE IF NOT EXISTS `devices` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`regid` varchar(300) NOT NULL,
`imei` varchar(50) NOT NULL,
`device_type` tinyint(2) NOT NULL,
`notification` tinyint(2) NOT NULL DEFAULT '1',
`is_active` tinyint(2) NOT NULL DEFAULT '0',
`activationcode` int(6) NOT NULL,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=28 ;
I Want to find the Sum( stickeruses
. count
) and COUNT( devices
. id
) for all appusers. 我想找到的总和(
stickeruses
。 count
)和COUNT( devices
。 id
)的所有appusers。
Here is my query. 这是我的查询。
SELECT `Appuser`.`id`, `Appuser`.`email`, `Appuser`.`country`, `Appuser`.`created`,
`Appuser`.`is_active`, SUM(`Stickeruse`.`count`) AS total, COUNT(`Device`.`id`)
AS tdevice
FROM `stickerapp`.`appusers` AS `Appuser`
LEFT JOIN `stickerapp`.`stickeruses` AS `Stickeruse`
ON (`Stickeruse`.`user_id`=`Appuser`.`id`)
INNER JOIN `stickerapp`.`devices` AS `Device`
ON (`Device`.`user_id`=`Appuser`.`id`)
WHERE `Appuser`.`is_active` = 1
GROUP BY `Appuser`.`id`
LIMIT 10
When I am applying each join separately the results are right, but I want to combine both joins. 当我分别应用每个联接时,结果是正确的,但是我想将两个联接合并。 And when I am doing it then results are wrong.
当我这样做时,结果是错误的。 please help.
请帮忙。
When mixing JOIN
and LEFT JOIN
it is a good idea to use parentheses to make it clear what your intent is. 混合
JOIN
和LEFT JOIN
,最好使用括号以使您清楚自己的意图。
I don't know what you need, but these syntaxes might give you different results: 我不知道您需要什么,但是这些语法可能会给您带来不同的结果:
FROM a LEFT JOIN ( b JOIN c ON b..c.. ) bc ON a..bc..
FROM ( a LEFT JOIN b ON a..b.. ) ab JOIN c ON ab..c..
Also, you can rearrange them do FROM a JOIN c LEFT JOIN b
(plus parentheses) or any of several other arrangements. 同样,您可以
FROM a JOIN c LEFT JOIN b
(加括号)或其他几种排列中重新排列它们。 Granted, some pairs rearrangements are equivalent. 当然,一些对重排是等效的。
Also, beware; 另外,要当心; aggregates (such as
SUM()
) get inflated values when JOIN
ing. JOIN
ing时,聚合(例如SUM()
)将获得膨胀值。 Think of it this way: first the JOIN
s get all appropriate combinations of rows from the tables, then the SUM
adds them up. 这样想:首先
JOIN
从表中获取所有适当的行组合,然后SUM
将它们加起来。 With that in mind, see if this works better: 考虑到这一点,看看它是否更好:
SELECT a.`id`, a.`email`, a.`country`, a.`created`, a.`is_active`,
( SELECT SUM(`count`)
FROM stickerapp.stickeruses
WHERE user_id = a.id
) AS total,
( SELECT COUNT(*)
FROM stickerapp.devices
WHERE user_id = a.id
) AS tdevice
FROM stickerapp.`appusers` AS a
WHERE a.`is_active` = 1
GROUP BY a.`id`
LIMIT 10
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