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社区首页 >问答首页 >如何显示不同的记录，我想要检查:如果布鲁伊德已经在表中显示数据只有一次与特定日期

问如何显示不同的记录，我想要检查:如果布鲁伊德已经在表中显示数据只有一次与特定日期
EN

Stack Overflow用户
提问于 2017-04-07 21:11:07
回答 2查看 28关注 0票数 0

表名:发现设备

代码语言：javascript
复制
+-----------+--------------+------+-----+-------------------+----------------+
| Field     | Type         | Null | Key | Default           | Extra          |
+-----------+--------------+------+-----+-------------------+----------------+
| id        | int(100)     | NO   | PRI | NULL              | auto_increment |
| blueid    | varchar(250) | NO   |     | NULL              |                |
| scannerid | varchar(250) | NO   |     | NULL              |                |
| datetime  | datetime     | NO   |     | CURRENT_TIMESTAMP |                |
+-----------+--------------+------+-----+-------------------+--------------


+--------------+--------------------------+---------------------+
| blueid       | scannerid                | datetime            |
+--------------+--------------------------+---------------------+
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 10:40:20 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 10:45:16 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 10:50:14 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 10:55:15 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:05:21 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:10:15 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:15:22 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:20:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:25:18 |
| Galaxy Note3 | CIS5040 Raspberry Device | 2017-04-07 11:30:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:50:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 11:55:16 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:18:16 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:20:15 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:27:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:28:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:29:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:30:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:31:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:32:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:33:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:34:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:35:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:36:14 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:38:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:39:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:40:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:41:15 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:42:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:43:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:44:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:45:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:46:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:47:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:48:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:49:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:50:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:51:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:52:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:53:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:54:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:55:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:56:20 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:57:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:58:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 12:59:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:00:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:01:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:02:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:03:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:04:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:06:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:07:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:08:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:09:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:10:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:11:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:12:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:13:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:14:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:15:17 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:16:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:17:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:18:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:19:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:20:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:21:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:22:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:23:14 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:24:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:25:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:26:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:27:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:28:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:29:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:31:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:32:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:33:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:35:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:36:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:37:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:38:19 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:39:12 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:40:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:41:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:42:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:43:14 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:44:18 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:45:13 |
| yuviandroid  | CIS5040 Raspberry Device | 2017-04-07 13:47:17 |
+--------------+--------------------------+---------------------+

我用了这个查询，

代码语言：javascript
复制
SELECT DISTINCT `blueid`,`scannerid`,`datetime`
FROM discovereddevices
WHERE date(datetime) = CURRENT_DATE.

现在，我如何才能得到不同的值，如yuviandroid，只有一次与特定日期。目前，考虑到时间因素，数据显示了不同的值。有人能给我建议一下。

mysql
sql
android
EN

回答 2

Stack Overflow用户

回答已采纳

发布于 2017-04-07 21:22:46

此查询将返回每个blueid的最大日期时间：

代码语言：javascript
复制
select blueid, max(datetime) as max_dt
from discovereddevices
where date(datetime) = CURRENT_DATE
group by blueid, date(datetime)

此查询将返回与最后一个日期时间关联的所有其他列：

代码语言：javascript
复制
select d.*
from
  discovereddevices d inner join (
    select blueid, max(datetime) as max_dt
    from discovereddevices
    where date(datetime) = CURRENT_DATE
    group by blueid
  ) l on d.blueid = l.blueid and d.datetime = l.max_dt
票数 0
EN

Stack Overflow用户

发布于 2017-04-07 21:15:26

如果你不想要的话，为什么要包括日期？

代码语言：javascript
复制
SELECT DISTINCT blueid, scannerid
FROM discovereddevices
WHERE date(datetime) = CURRENT_DATE;
票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/43287150

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