Mysql SQL将两列分组并选择最近的日期/时间戳
所以我有一张叫做电话留言的桌子。这是我编写的一个示例查询。我要做的是将具有character\u id 22或target\u character\u id 22的行组合在一起。因为在数据库中存储的每个phone_消息中有两个条目。基本上是电话交谈。我想做的是让小组获得每个小组发送的最后一条消息 我的原始查询:Mysql SQL将两列分组并选择最近的日期/时间戳,mysql,sql,Mysql,Sql,所以我有一张叫做电话留言的桌子。这是我编写的一个示例查询。我要做的是将具有character\u id 22或target\u character\u id 22的行组合在一起。因为在数据库中存储的每个phone_消息中有两个条目。基本上是电话交谈。我想做的是让小组获得每个小组发送的最后一条消息 我的原始查询: SET @character_id = 22; SET @t = 'text'; SELECT character_id, target_character_id, message,
SET @character_id = 22;
SET @t = 'text';
SELECT character_id, target_character_id, message, `type`, MAX(`date`) date FROM
`phone_messages`
WHERE
(
`character_id`=@character_id
) AND `type`=@t
GROUP BY
character_id, target_character_id
我对此的期望输出是
character_id | target_character_id | message | type | date
"33" "22" "perfect see you then" "text" "2020-08-25 23:28:43"
"22" "57" "the tool shop down south" "text" "2020-09-05 19:05:45"
我该怎么做呢?对不起,我对我的问题缺乏理解。我只是想确认一下
- 每对呼叫者(其中一人为“22”)
- 你想得到最新的文本,无论是哪种方式(从22到22)
- 对于每一行,确定另一方(在查询中称为
)second\u character\u id
- 对于其他各方,根据发送日期对“文本”行进行排序
- 获取每一方的最新行
主要字符\u id
——在本例中始终是22——以防您希望将其扩展为多人
下面是一个关于数据设置和方法的示例
请注意,在底部还有一个额外的查询-这是我之前的尝试,我误解了需求。在该答案中,它将查找到22的最新“传入”和最新“传出”文本,而不管它们来自谁。如果您想要每对的最新消息,无论顺序如何,那么您可以使用
行号()
和最小值()
和最大值()
:
character_id | target_character_id | message | type | date
"33" "22" "perfect see you then" "text" "2020-08-25 23:28:43"
"22" "57" "the tool shop down south" "text" "2020-09-05 19:05:45"
WITH Call_list AS
(SELECT *,
@character_id AS `primary_character_id`,
CASE
WHEN `character_id` = @character_id THEN `target_character_id`
ELSE `character_id` END AS `second_character_id`
FROM
`phone_messages`
WHERE
(`character_id`= @character_id OR `target_character_id`= @character_id)
AND (`type`= @t )
),
Sorted_Call_List AS
(SELECT *,
ROW_NUMBER() OVER
(PARTITION BY `primary_character_id`, `second_character_id`
ORDER BY `Date` DESC
) AS char_rn
FROM Call_list
)
SELECT `character_id`, `target_character_id`, `message`, `type`, `date`
FROM Sorted_Call_List
WHERE char_rn = 1;
SET @character_id = 22;
SET @t = 'text';
SELECT pm.*
FROM (SELECT pm.*,
ROW_NUMBER() OVER (PARTITION BY LEAST(character_id, target_character_id), GREATEST(character_id, target_character_id)
ORDER BY date DESC
) as seqnum
FROM phone_messages pm
WHERE character_id = @character_id AND
type = @t
) pm
WHERE seqnum = 1;