BatteryId TimeStamp Temprature
1 2017-02-13 12:16:14.000 23
1 2016-02-13 12:13:14.000 21
1 2015-01-13 12:16:14.000 19
2 2017-02-11 12:16:14.000 22
2 2016-02-13 12:16:14.000 16
3 2017-02-13 11:16:14.000 12
3 2016-02-13 12:15:14.000 25
我有多个记录,每个电池如上 下面的SQL查询表对每个电池选择最新的记录使用SQL与计数每个电池
SELECT * FROM (SELECT BatteryId, Timestamp, Temperature
ROW_NUMBER() OVER(PARTITION BY BatteryId ORDER BY timestamp DESC)
AS N FROM tblBattery) AS TT WHERE N = 1
返回最新的纪录
BatteryId TimeStamp Temprature
1 2017-02-13 12:16:14.000 23
2 2017-02-11 12:16:14.000 22
3 2017-02-13 11:16:14.000 12
如何为每个BatteryId添加Count,以下是我需要的内容
BatteryId TimeStamp Temprature Count
1 2017-02-13 12:16:14.000 23 3
2 2017-02-11 12:16:14.000 22 2
3 2017-02-13 11:16:14.000 12 2
我删除了mysql标签,因为语法看起来像sql-server。 –
这里有问题吗? – OldProgrammer
肯定是从Tajinder看到下面的答案 –