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MS SQL Calculate 2 values in same column different that groups by datetime (hourly)

I have database MS2008 that has a table called HISTORY2012. These contain thousands of rows of historical data. Most important columns are DATASETNAME which is varchar(20), VALUE which is varchar(12) that I have to convert to FLOAT, and TIME that is a datetime (yyyy-mm-dd hh:mm:ss). I need to take the VALUES of rows based on TIME of hourly even though there is data that has times that are every 15 seconds for instance every hour I need to take DATASETNAME that is = 'GCECLD' and DATASETNAME that = 'EPCOLD' each has values and subtract them for the new column called GCERCOT But I only want on the hour. I also need to display the date. So I know this would be a GROUP BY effort. But I am stuck

DATASETNAME          VALUE          TIME
GCECLD                       125.23         2012-01-01 00:00:00
GCECLD                       125.65         2012-01-01 00:00:15
EPCOLD                       19.12           2012-01-01 00:00:00
GCECLD                       125.65         2012-01-01 00:00:30
GCECLD                       125.65         2012-01-01 00:00:45
GCECLD                       125.65         2012-01-01 00:01:00
.
.
.
GCECLD                       129.65         2012-01-01 01:00:00
EPCOLD                       18.12           2012-01-01 01:00:00
All the way through the end of the year.

So the output would be:
DATE               TIME                    GCERCOT
01-01-2012    00:00:00               106.11
01-01-2012    01:00:00               111.53

I hope I have given as much detail as I can. I know some basics in Selecting and queries but Math functions and grouping still escape me. Thanks.
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rayburnelectric
Asked:
rayburnelectric
1 Solution
 
SThayaCommented:
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rayburnelectricAuthor Commented:
I have other DATASETNAMES like TVECLC,FECLD etc. that have values in same date hour range. This doesn't fix issue with grouping by TIME. I will be calling the view from a Web Page but need to test it in SQL management Studio first.
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Guy Hengel [angelIII / a3]Billing EngineerCommented:
You want to GROUP BY HOUR(time), CONVERT(VARCHAR(10), time, 120)
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rayburnelectricAuthor Commented:
ok But I need the full SELECT STATEMENT on getting the columns with those where clauses to subtract the value.
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Ioannis ParaskevopoulosCommented:
Hi,

Try this

SELECT	CONVERT(VARCHAR(10),[TIME],101) AS DateOnly,
		CONVERT(VARCHAR(8),CONVERT(DATETIME,DATEADD(hh,DATEPART(hh, [TIME]),CONVERT(VARCHAR(10),[TIME],101))),108),
		SUM(CASE WHEN DATASETNAME = 'GCECLD' THEN CONVERT(FLOAT,[VALUE]) END) AS 'GCECLD',
		SUM(CASE WHEN DATASETNAME = 'EPCOLD' THEN CONVERT(FLOAT,[VALUE]) END) AS 'EPCOLD',
		SUM(CASE WHEN DATASETNAME = 'GCECLD' THEN CONVERT(FLOAT,[VALUE]) END) -
		SUM(CASE WHEN DATASETNAME = 'EPCOLD' THEN CONVERT(FLOAT,[VALUE]) END) AS 'GCERCOT '
FROM	HISTORY2012
GROUP BY CONVERT(VARCHAR(10),[TIME],101),
		DATEPART(hh, [TIME])

Open in new window


Giannis
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rayburnelectricAuthor Commented:
This was Close. The query takes a bit. But it does not ORDER BY DATE THEN TIME. Also I need to be able to pass a variable to it I may several scenarios where I am subtracting one DATASETNAME from another based on hourly values.
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Ioannis ParaskevopoulosCommented:
Hi,

Does this cover you?

DECLARE @Minuend AS VARCHAR(20)
DECLARE @Subtrahend AS VARCHAR(20)
SET @minuend 	= 'GCECLD'
SET @subtrahend = 'EPCOLD'
SELECT	CONVERT(VARCHAR(10),[TIME],101) AS DateOnly,
		CONVERT(VARCHAR(8),CONVERT(DATETIME,DATEADD(hh,DATEPART(hh, [TIME]),CONVERT(VARCHAR(10),[TIME],101))),108),
		SUM(CASE WHEN DATASETNAME = @minuend THEN CONVERT(FLOAT,[VALUE]) END) AS Minuend ,
		SUM(CASE WHEN DATASETNAME = @subtrahend THEN CONVERT(FLOAT,[VALUE]) END) AS Subtrahend,
		SUM(CASE WHEN DATASETNAME = @minuend THEN CONVERT(FLOAT,[VALUE]) END) -
		SUM(CASE WHEN DATASETNAME = @subtrahend THEN CONVERT(FLOAT,[VALUE]) END) AS 'difference'
FROM	zz_test1
GROUP BY CONVERT(VARCHAR(10),[TIME],101),
		DATEPART(hh, [TIME])
ORDER BY  CONVERT(VARCHAR(10),[TIME],101),
		DATEPART(hh, [TIME])

Open in new window



Giannis
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rayburnelectricAuthor Commented:
That worked for most part. I will be building the query into a view or from Razor. Just takes about 17 seconds. Also ORDER BY 1,2 ASC orders it by first and seconds column. Thank you.
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Ioannis ParaskevopoulosCommented:
Hi,

Thanks. Keep in mind that although ORDER BY 1,2 could be a quick way to do it, but you should consider what if you ever put an extra column before them? the order will break. If you explicitly state how you order the results, you won't have to worry for that case.

ORDER BY 1,2 is fine though for most cases.

Giannis
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rayburnelectricAuthor Commented:
Very true. This query will populate a chart in essence I would only need DATE TIME and The difference value.
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