Question

我似乎无法围绕我需要开发的SQL查询。我需要计算传感器在规定时间内超过限制的时间百分比。

我表格中的数据如下所示：

Id,          TimeStamp,  Value,    SensorName 
1,  2018-03-16 00:00:01,    45,  Temperature1 
2,  2018-03-16 00:00:01,    53,  Temperature2    
3,  2018-03-16 00:00:02,    46,  Temperature1    
4,  2018-03-16 00:00:02,    54,  Temperature2    
4,  2018-03-16 00:00:03,    45,  Temperature1    
5,  2018-03-16 00:00:04,    46,  Temperature1    
6,  2018-03-16 00:00:05,    45,  Temperature2

..........

每个传感器通常每秒都有一条记录，但如果传感器值没有变化，记录可能会减少。

我怎么能写一个查询，告诉我在过去一小时内Temperature1大于45的时间百分比？提前谢谢。

Answer 1

将@temp替换为您的表名

select (cast(e.exceed as float)/cast(t.tot as float)) * 100.00 as [% exceed] from
(
select count(*) exceed
from @temp
where
SensorName = 'temperature1'
and TimeStamp between '2018-03-16 00:00:01' and '2018-03-16 00:00:02'
and Value > 45) e,

(
select count(*) tot
from @temp
where
SensorName = 'temperature1'
and TimeStamp between '2018-03-16 00:00:01' and '2018-03-16 00:00:02'
) t

Answer 2

将SUM与条件值一起使用：

Declare @t table (Id int,[TimeStamp] datetime, [Value] int, SensorName nvarchar(30))
insert into @t values
  (1,'2018-03-16 00:00:01',45,'Temperature1')
, (2,'2018-03-16 00:00:01',53,'Temperature2')
, (3,'2018-03-16 00:00:02',46,'Temperature1')
, (4,'2018-03-16 00:00:02',54,'Temperature2')
, (4,'2018-03-16 00:00:03',45,'Temperature1')
, (5,'2018-03-16 00:00:04',46,'Temperature1')
, (6,'2018-03-16 00:00:05',45,'Temperature2')

Declare @tempvalue int = 45

select sum(iif([Value]>@tempvalue,1.0,0.0))/count(*)*100
from @t
where SensorName = 'Temperature1'

SQL查询 - 状态时间

2 个答案: