我正在编写SQL查询以根据以下要求显示不同类型的结果：
示例数据：
+----------+-------------+-------------+ | DeviceId | CaptureTime | SensorValue | +----------+-------------+-------------+ | DC001 | 02/01/2017 | 0 | | DC001 | 02/02/2017 | 1 | | DC001 | 02/03/2017 | 0 | | DC001 | 02/04/2017 | 1 | | DC001 | 02/05/2017 | 0 | | DC001 | 02/07/2017 | 1 | | DC001 | 02/08/2017 | 0 | | DC001 | 02/10/2017 | 1 | | DC001 | 02/01/2017 | 0 | | DC001 | 02/01/2017 | 0 | | DC002 | 02/02/2017 | 1 | | DC002 | 02/02/2017 | 0 | | DC002 | 02/02/2017 | 1 | | DC002 | 02/02/2017 | 1 | | DC002 | 02/02/2017 | 1 | | DC002 | 02/03/2017 | 1 | | DC002 | 02/03/2017 | 0 | | DC002 | 02/03/2017 | 0 | | DC002 | 02/03/2017 | 1 | | DC002 | 02/03/2017 | 1 | | DC003 | 02/03/2017 | 1 | | DC003 | 02/03/2017 | 1 | | DC003 | 02/03/2017 | 0 | | DC003 | 02/03/2017 | 1 | | DC003 | 02/03/2017 | 1 | | DC003 | 02/04/2017 | 1 | | DC003 | 02/05/2017 | 1 | | DC003 | 02/06/2017 | 1 | | DC003 | 02/07/2017 | 1 | | DC003 | 02/08/2017 | 1 | | DC004 | 02/09/2017 | 0 | | DC004 | 02/10/2017 | 0 | | DC004 | 02/11/2017 | 1 | | DC004 | 02/12/2017 | 0 | | DC004 | 02/12/2017 | 1 | | DC004 | 02/12/2017 | 1 | | DC004 | 02/12/2017 | 1 | | DC004 | 02/12/2017 | 1 | | DC004 | 02/12/2017 | 1 | | DC004 | 02/12/2017 | 1 | | DC005 | 02/12/2017 | 0 | | DC005 | 02/12/2017 | 0 | | DC005 | 02/12/2017 | 0 | | DC005 | 02/12/2017 | 0 | | DC005 | 02/14/2017 | 0 | | DC005 | 02/14/2017 | 0 | | DC005 | 02/14/2017 | 0 | | DC005 | 02/14/2017 | 0 | | DC005 | 02/14/2017 | 0 | | DC005 | 02/14/2017 | 0 | +----------+-------------+-------------+
我已经为所有三个要求创建了以下常见查询：
DECLARE @HoursBack INT
, @MinMax VARCHAR(3)
, @TopRows INT
SELECT TOP (@TopRows) COUNT(TD1.DeviceId) PickedNoOfTimes, ItemName -- I have removed table to get ItemName to simplify this query
FROM tTrayDetails AS TD1
WHERE TD1.SensorValue = 0
AND TD1.CaptureTime > DATEADD(HOUR, -@HoursBack, GETDATE())
AND TD1.SensorValue <> (
SELECT TOP 1 SensorValue
FROM tTrayDetails TD2
WHERE TD2.CaptureTime < TD1.CaptureTime
ORDER BY TD2.CaptureTime DESC
)
GROUP BY TD1.DeviceId
ORDER BY CASE WHEN @MinMax = 'Max' THEN COUNT(TD1.DeviceId) END DESC
, CASE WHEN @MinMax = 'Min' THEN COUNT(TD1.DeviceId) END ASC
DECLARE @HoursBack INT
, @MinMax VARCHAR(3)
, @TopRows INT
SELECT TOP (@TopRows) COUNT(TD1.DeviceId) PickedNoOfTimes, ItemName -- I have removed table to get ItemName to simplify this query
FROM tTrayDetails AS TD1
WHERE TD1.SensorValue = 0
AND TD1.CaptureTime > DATEADD(HOUR, -@HoursBack, GETDATE())
AND TD1.SensorValue <> (
SELECT TOP 1 SensorValue
FROM tTrayDetails TD2
WHERE TD2.CaptureTime < TD1.CaptureTime
ORDER BY TD2.CaptureTime DESC
)
GROUP BY TD1.DeviceId
ORDER BY CASE WHEN @MinMax = 'Max' THEN COUNT(TD1.DeviceId) END DESC
, CASE WHEN @MinMax = 'Min' THEN COUNT(TD1.DeviceId) END ASC
此查询适用于所有三个要求，只需设置@HoursBack，@ MinMax和@TopRows变量的不同值。
以下是为我的三个要求设置的值：
现在问题：此查询大约需要40秒执行，仅适用于测试环境中的14K记录。
在生产环境中，每天会添加2-4K记录，因此查询执行时间会增加。
如何使用大量数据更改查询以更快地运行。
答案 0 :(得分：2)
这将仅计算SensorValue从1更改为0的那些行：
WITH cte AS
(
SELECT DeviceId,
-- previous row = 1 and current row = 0
CASE WHEN LAG(SensorValue)
Over (PARTITION BY DeviceId
ORDER BY CaptureTime) = 1
AND SensorValue = 0
THEN 1
ELSE 0
END AS ChangeFlag
FROM tTrayDetails AS t
WHERE ....
)
SELECT DeviceId, Count(*)
FROM cte
WHERE ChangeFlag = 1
GROUP BY DeviceId
现在应用您的TOP / ORDER BY ...
答案 1 :(得分：1)
这是：
declare
@topRows int = 2,
@minMax nvarchar(3) = 'max',
@hoursBack int = 1000,
@now datetime = getdate();
;with _raw
as (
select
DeviceId,
case when SensorValue = 0 and lag(SensorValue) over (partition by DeviceId order by CaptureTime) = 1
then 1
else 0
end as Val
from tTrayDetails
where
CaptureTime > dateadd(hour, -@hoursBack, @now)
)
, _combined
as (
select
DeviceId,
sum(Val) as Val,
(case when @minMax = 'min' then 1 else -1 end) * sum(Val) as Ord
from _raw
group by
DeviceId
)
select top(@topRows)
DeviceId, Val
from _combined
order by
Ord, DeviceId
和测试脚本一样：
create table #tTrayDetails
(
DeviceId nvarchar(128),
CaptureTime datetime not null,
SensorValue int not null
)
insert into #tTrayDetails(DeviceId, CaptureTime, SensorValue) values
('DC001', '2017-01-01 01:00:00', 0),
('DC001', '2017-01-01 02:00:00', 1),
('DC001', '2017-01-02 01:00:00', 0),
('DC001', '2017-01-03 01:00:00', 1),
('DC001', '2017-01-04 01:00:00', 0),
('DC002', '2017-01-01 01:00:00', 0),
('DC002', '2017-01-01 02:00:00', 0),
('DC002', '2017-01-01 03:00:00', 1),
('DC002', '2017-01-01 04:00:00', 1),
('DC002', '2017-01-01 05:00:00', 1),
('DC002', '2017-01-01 06:00:00', 0),
('DC003', '2017-01-01 06:00:00', 0)
declare
@topRows int = 2,
@minMax nvarchar(3) = 'max',
@hoursBack int = 1000,
@now datetime = getdate();
;with _raw
as (
select
DeviceId,
case when SensorValue = 0 and lag(SensorValue) over (partition by DeviceId order by CaptureTime) = 1
then 1
else 0
end as Val
from #tTrayDetails
where
CaptureTime > dateadd(hour, -@hoursBack, @now)
)
, _combined
as (
select
DeviceId,
sum(Val) as Val,
(case when @minMax = 'min' then 1 else -1 end) * sum(Val) as Ord
from _raw
group by
DeviceId
)
select top(@topRows)
DeviceId, Val
from _combined
order by
Ord, DeviceId
drop table #tTrayDetails