繁体   English   中英

SQL Select,每分钟仅一条记录

[英]SQL Select, only one record per minutes

我在PHP中选择了这样的SQL:

$sql_GATE  = $conn->query("SELECT  * FROM GATE WHERE st='ff0000' and dataGate between '2018-06-27 00:00:0' and '2018-06-27 23:59:0' order by id desc ");

这段代码返回给我大约120000条记录,例如:

1-ff0000-->2018-06-27 18:28:51<br>
2-ff0000-->2018-06-27 18:28:51<br>
3-ff0000-->2018-06-27 18:28:51<br>
13-ff0000-->2018-06-27 18:28:49 .......

如何编写SQL请求,每1分钟或2分钟仅返回一条记录? 因为在一秒钟内大约有3条记录

这里有语法和示例:

SELECT col1, col2, col3, colN, MAX(TimeAndDateColumn)
FROM table
GROUP BY DATE(TameAndDateColumn), HOUR(TimeAndDateColumn), Minute(TimeAndDateColumn)

例:

SELECT id, latitute, longitude, speed, MAX(`time`)
FROM YourTableName
GROUP BY DATE(`time`), HOUR(`time`), Minute(`time`)

暂无
暂无

声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.

 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM