我有 5 个表（为问题设计和简化）：
Device
---------------
DeviceID - INT IDENTITY - PRIMARY KEY
DeviceGUID - UNIQUEIDENTIFIER - UNIQUE CLUSTERED (used for lookups)
OtherInfo
Device_State
---------------
DeviceStateID - INT IDENTITY - PRIMARY KEY
DeviceID - INT - FOREIGN KEY - UNIQUE CLUSTERED (used for lookups)
Pump1 - TINYINT
Pump2 - TINYINT
Pump3 - TINYINT
Pump4 - TINYINT
Pump5 - TINYINT
Heater1 - TINYINT
Heater2 - TINYINT
Lights - BIT
TimeStamp - SMALLDATETIME
Device_State_History
---------------
DeviceStateHistoryID - INT IDENTITY - PRIMARY KEY
DeviceStateID - INT - FOREIGN KEY - NONCLUSTERED INDEX (used for lookups)
Pump1 - TINYINT
Pump2 - TINYINT
Pump3 - TINYINT
Pump4 - TINYINT
Pump5 - TINYINT
Heater1 - TINYINT
Heater2 - TINYINT
Lights - BIT
TimeStamp - SMALLDATETIME
Peripheral_State
----------------
PeripheralStateID - INT IDENTITY - PRIMARY KEY
DeviceID - INT - FOREIGN KEY - UNIQUE CLUSTERED (used for lookups)
Pump1 - TINYINT
Pump2 - TINYINT
PH - SMALLINT
ORP - SMALLINT
ELECTRODEID - TINYINT
ELECTRODEPOLARITY - TINYINT
TimeStamp - SMALLDATETIME
Peripheral_State_History
----------------
PeripheralStateHistoryID - INT IDENTITY - PRIMARY KEY
PeripheralStateID - INT - FOREIGN KEY - NONCLUSTERED INDEX (used for lookups)
Pump1 - TINYINT
Pump2 - TINYINT
PH - SMALLINT
ORP - SMALLINT
ELECTRODEID - TINYINT
ELECTRODEPOLARITY - TINYINT
TimeStamp - SMALLDATETIME
情况如下：
Device_State_History 表中有约 380 万条记录，Peripheral_State_History 表中有约 10 万条记录。
我想编写一个查询，在给定日期时间之间选择给定 DeviceGUID 的所有 Peripheral_State_history 和 Device_State_History。我想获得这样的记录：
Select
Peripheral_State_History.PH,
Peripheral_State_History.ORP,
(
if(Device_State_History.Pump1 == 1 ||
Device_State_History.Pump2 == 1 ||
Device_State_History.Pump3 == 1 ||
Device_State_History.Pump4 == 1 ||
Device_State_History.Pump5 == 1
)
{ 1 }
else
{ 0 }
) AS PumpsOn,
TimeStamp
FROM CombinedData
此外，Device_State_History 和 Peripheral_State_History 之间的时间戳并不总是相同的。我的意思是，Device_State_History 表中 1 个设备的记录时间戳可能是这样的：
Mar-1-2013 12:31
Mar-1-2013 12:33
Mar-1-2013 12:36
Mar-1-2013 12:38
Mar-1-2013 12:41
然后Peripheral_State_History表中就会有记录：
Mar-1-2013 12:29
Mar-1-2013 12:33
Mar-1-2013 12:34
Mar-1-2013 12:38
Mar-1-2013 12:39
Mar-1-2013 12:41
如您所见，时间戳并不总是重叠。
我一直在阅读并尝试编写存储过程来执行此操作，但是，这超出了我的 SQL 能力，非常感谢指导和示例。谢谢。
编辑：
以下是我编写的用于从 Peripheral_State_History 表中获取数据的存储过程。它不包括我想要的 Device_State_History 表中的 Pump 数据。
需要注意的几件事：每个时间戳我只获得 1 条记录，因为有一些带有多条记录的时间戳。此存储过程从 State 表中获取当前记录，以及从历史表中获取所有记录。
USE my_db
GO
IF EXISTS (SELECT * FROM sys.objects WHERE type = 'P' AND name = 'SP_Select_Stuff')
DROP PROCEDURE 'SP_Select_Stuff')
GO
CREATE PROCEDURE 'SP_Select_Stuff')
(
@DeviceGUID uniqueidentifier
)
AS
DECLARE @RetCode INT
;WITH combined AS
(
SELECT
ROW_NUMBER() OVER
(PARTITION BY [TimeStamp] ORDER BY [TimeStamp]) as num, ORP, PH, [TimeStamp]
FROM Peripheral_State
INNER JOIN Device
ON Peripheral_State.DeviceID = Device.DeviceID
WHERE Device.DeviceGUID = @DeviceGUID
UNION ALL
SELECT
ROW_NUMBER() OVER
(PARTITION BY [TimeStamp] ORDER BY [TimeStamp]) as num, ORP, PH, [TimeStamp]
FROM Peripheral_State_History
INNER JOIN Device
ON Peripheral_State.DeviceID = Device.DeviceID
WHERE Device.DeviceGUID = @DeviceGUID
)
SELECT ORP, PH, [TimeStamp]
FROM combined
WHERE ORP > 0
AND PH > 0
AND combined.num = 1
ORDER BY [TimeStamp] ASC
IF @@ERROR <> 0
BEGIN
SET @RetCode = 5
RETURN @RetCode
END
ELSE
BEGIN
SET @RetCode = 0
RETURN @RetCode
END
GO
编辑：
这是我想出的。
USE my_db
--"combined" gets all of the data.
--A row from the peripheral history will look like: ORP-Value, PH-Value, Current-Value, NULL, TimeStamp.
--A row from the device history will look like: NULL, NULL, NULL, PumpsOn-Value, TimeStamp
-- I also get a num for filtering 1 TimeStamp per minute. My TimeStamps are accurate to the minute, so if one minute has 30 records, I will use the first record.
;WITH combined AS
(
SELECT
ROW_NUMBER() OVER
(PARTITION BY ph.[TimeStamp] ORDER BY ph.[TimeStamp]) as num, ph.ORP, ph.PH, ph.[Current], NULL as PumpsOn, ph.[TimeStamp]
FROM Device as d
LEFT JOIN Peripheral_State as ps
ON ps.DeviceID = d.DeviceID
LEFT JOIN Peripheral_State_History as ph
ON ph.DeviceID = d.DeviceID
WHERE d.DeviceGUID = @DeviceGUID
AND ph.TimeStamp BETWEEN '2013-03-02 00:00:00' AND GETDATE()
UNION ALL
SELECT
ROW_NUMBER() OVER
(PARTITION BY dh.[TimeStamp] ORDER BY dh.[TimeStamp]) as num, NULL as ORP, NULL as PH, NULL as [Current], IsNull(COALESCE(dh.Pump1, dh.Pump2, dh.Pump3, dh.Pump4, dh.Pump5),0) as PumpsOn, dh.[TimeStamp]
FROM Device as d
LEFT JOIN Device_State as ds
ON ds.DeviceID = d.DeviceID
LEFT JOIN Device_State_History as dh
ON dh.DeviceID = d.DeviceID
WHERE d.DeviceGUID = @DeviceGUID
AND ph.TimeStamp BETWEEN '2013-03-02 00:00:00' AND GETDATE()
),
--"FilteredAndAddID" gets a record set that has an ID added to the row. This is required for the 3rd step.
--It also filters the data so that records with 0 orp/ph are omitted.
FilteredAndAddID AS
(
SELECT
ROW_NUMBER() OVER (ORDER BY [TimeStamp]) as ID,
ORP,
PH,
[Current],
PumpsOn,
[TimeStamp]
FROM combined
WHERE
(ORP is NULL OR ORP > 0) AND (PH is NULL OR PH > 0)
AND combined.num = 1
),
--"filled" is used to fill the "FilteredAddID" record set NULLS with the previous row that has a value instead of NULL.
filled AS
(
SELECT Curr.ID,
ISNULL(Curr.ORP, (SELECT TOP 1 ORP FROM FilteredAddID WHERE ID < Curr.ID AND ORP IS NOT NULL ORDER BY ID)) ORP,
ISNULL(Curr.PH, (SELECT TOP 1 PH FROM FilteredAddID WHERE ID < Curr.ID AND PH IS NOT NULL ORDER BY ID)) PH,
ISNULL(Curr.[Current], (SELECT TOP 1 [Current] FROM FilteredAddID WHERE ID < Curr.ID AND [Current] IS NOT NULL ORDER BY ID)) [Current],
ISNULL(Curr.PumpsOn, (SELECT TOP 1 PumpsOn FROM FilteredAddID WHERE ID < Curr.ID AND PumpsOn IS NOT NULL ORDER BY ID)) PumpsOn,
Curr.[TimeStamp]
FROM FilteredAddID Curr
)
SELECT ID, ORP, PH, [Current], PumpsOn, [TimeStamp]
FROM filled
ORDER BY [TimeStamp] ASC
前 2 个查询“组合”和“FilterAndAddID”在毫秒内执行，但是“填充”查询大约需要 6 分钟来填充约 1700 条记录中的空值。
有没有办法加快这个速度？
我以正确的方式接近这个吗？
理想情况下，我需要它在几秒钟内运行。