[英]MySQL - Query not returning proper results
CREATE TABLE `swipes` (
`swp_id` bigint(20) NOT NULL,
`swp_by` bigint(20) NOT NULL,
`swp_to` bigint(20) NOT NULL,
`swp_type` varchar(255) NOT NULL,
`swp_status` enum('requested','accepted','declined') NOT NULL,
`swp_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `swipes` (`swp_id`, `swp_by`, `swp_to`, `swp_type`, `swp_status`, `swp_date`) VALUES
(1, 8, 11, 'top', 'accepted', '2020-04-18 20:48:45'),
(2, 1, 11, 'right', 'accepted', '2020-04-18 20:41:49'),
(3, 12, 1, 'right', 'accepted', '2020-04-18 20:41:49'),
(4, 13, 1, 'right', 'accepted', '2020-04-18 20:41:49'),
(5, 1, 14, 'right', 'accepted', '2020-04-18 20:41:49'),
(6, 1, 15, 'top', 'accepted', '2020-04-18 20:41:49');
CREATE TABLE `messages` (
`msg_id` bigint(20) NOT NULL,
`msg_from` bigint(20) NOT NULL,
`msg_to` bigint(20) NOT NULL,
`msg_message` longtext NOT NULL,
`msg_seen` enum('yes','no') NOT NULL DEFAULT 'no',
`msg_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `messages` (`msg_id`, `msg_from`, `msg_to`, `msg_message`, `msg_seen`, `msg_time`) VALUES
(1, 11, 1, 'How are you?', 'yes', '2020-04-14 21:01:05'),
(3, 1, 11, 'I am fine.. you?', 'no', '2020-04-14 20:54:07'),
(4, 1, 8, 'How are you?', 'yes', '2020-04-14 21:01:05'),
(5, 8, 1, 'I am good... You say?', 'yes', '2020-04-14 21:13:34'),
(6, 1, 11, 'Thik hun... Tum batao..', 'yes', '2020-04-14 21:16:05'),
(7, 11, 1, 'Okay', 'yes', '2020-04-16 09:16:39'),
(8, 8, 1, 'Yes, it\'s a good idea.', 'yes', '2020-04-16 09:16:39'),
(9, 1, 8, 'Thought so.. Would you like to join?', 'yes', '2020-04-16 09:23:39'),
(10, 8, 1, 'Are you there?', 'yes', '2020-04-23 11:57:39'),
(12, 8, 1, 'Would you like to join?', 'yes', '2020-04-23 10:42:27'),
(13, 1, 11, 'We will arrange things for you :)', 'yes', '2020-04-23 10:59:04');
小提琴: DB FIDDLE
在上面的小提琴中,我的查询返回了正确的数据,但是当 1 出现在swp_by
在 swipes 表中的多个记录中时,它似乎消除了结果。 起初我以为是因为GROUP BY swipes.swp_by
但我删除了它,看起来这不是问题所以我把它放回去了。 当您运行查询时,您会看到当前查询返回swp_id
2, 3 & 4
但不返回5 & 6
的结果。 它们被淘汰了,这是因为在swp_by
1
中出现了swp_id
2
一次。 我希望查询也返回5 & 6
的结果。
询问
SELECT
swp_id,
swp_by,
swp_to,
msg_from,
msg_to,
msg_message,
GREATEST(MAX(msg_time), swipes.swp_date) AS msgdate,
COUNT(msg_id) AS msgcnt
FROM
swipes
LEFT JOIN
(SELECT
*
FROM
messages
ORDER BY msg_time DESC) messages ON ((messages.msg_from = swipes.swp_by
AND messages.msg_to = swipes.swp_to)
OR (messages.msg_from = swipes.swp_to
AND messages.msg_to = swipes.swp_by))
WHERE
(swipes.swp_by = 1 OR swipes.swp_to = 1)
AND swipes.swp_status = 'accepted'
GROUP BY swipes.swp_by
ORDER BY GREATEST(MAX(messages.msg_time),
MAX(swipes.swp_date)) DESC
这是怎么回事?
我正在建立一个聊天系统,匹配的用户可以互相聊天。 swipes
存储匹配项,消息是用户之间的交易消息。 通过此查询,我试图设置匹配用户的主页列表,以便在您点击/单击用户的位置聊天,然后出现聊天框(稍后会这样做)。 我认为只是简要介绍该项目可能有助于理解问题。
我在这里发布我的答案小提琴没有给出正确的链接
不知道https://www.db-fiddle.com/f/2yKt6d5RWngXVYJKPGZL6m/2
SELECT
swp_id,
swp_by,
swp_to,
msg_from,
msg_to,
msg_message ,
GREATEST(MAX(msg_time), swipes.swp_date) AS msgdate,
COUNT(msg_id) AS msgcnt
FROM
swipes
LEFT JOIN
(SELECT
*
FROM
messages
ORDER BY msg_time DESC) messages
ON (messages.msg_from = swipes.swp_by
AND messages.msg_to = swipes.swp_to)
OR
(messages.msg_from = swipes.swp_to
AND messages.msg_to = swipes.swp_by)
WHERE
(swipes.swp_by = 1 OR swipes.swp_to = 1)
AND swipes.swp_status = 'accepted'
GROUP BY swipes.swp_by,swipes.swp_to
ORDER BY GREATEST(MAX(messages.msg_time),
MAX(swipes.swp_date)) DESC
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