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Converting Time value stored in minutes Expand / Collapse
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Posted Thursday, July 8, 2010 10:18 AM


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In the source system the date and time is stored as an integer representing the number of minutes AD. I have been unable to tie out to the date and time value.

Minutes = 1056915413

The application that uses this data displays it as 6/30/2010 19:53 (CDT). The metadata indicates the time is stored as UTC so the minutes should equal - 2010-07-01 01:53:00.000

Manual calculations:
--(1440*365.25) minutes per year = 525960.00

-- get year, add 1 since start date should be 1-1-0001
SELECT (1056915413/525960)+1

-- minutes based on remainder
SELECT (1056915413%525960)

-- add minutes remaining to midnight on jan 1, 2010
SELECT DATEADD(n,261773,'2010-01-01 00:00:00')

Results:

-----------
2010

(1 row(s) affected

---------------------------------------
261773.00

(1 row(s) affected)

-----------------------
2010-07-01 18:53:00.000

(1 row(s) affected)


Is there a function in SQL or a standard method to determine this.

I tried the following C#:
            DateTime startDT = new DateTime(0001, 1, 1, 0, 0, 0);
TimeSpan span = new TimeSpan(0, 1056915413, 0);

textBox1.Text = Convert.ToString(startDT+span);


This returned 7/17/2010 0:53:00 AM

The minutes are correct in both examples. Any suggestions would be great.
Post #949424
Posted Thursday, July 8, 2010 11:58 AM


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You could make a UDF that contains the logic and then use it inline. Primary contents would be


DECLARE
@jDate INT,
@jBase INT
SET @jBase = 998799780 -- 1900-01-01

SET @jDate = 1056915413 -- this is the parameter you set to your incoming 'number'

SELECT DATEADD(n, (@jDate - @jBase), '1900-01-01 00:00')

HTH,




Steve.
Post #949492
Posted Thursday, July 8, 2010 12:05 PM


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How about correcting for the time zone? Maybe I'm not getting your question, but would something like this work:

SELECT dateadd(ss,(DATEDIFF(ss,GETDATE(),GETUTCDATE())),(DATEADD(n,261773,'2010-01-01 00:00:00')))

Post #949500
Posted Thursday, July 8, 2010 12:44 PM


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Since you posted in a SQL 2005 forum, I'm assuming that you are on that version, which means that the sql 2008 date/time enhancements won't help you:
declare @minutes int = 1056915413
declare @test datetime2 = '01/01/0001'
select DATEADD(minute, @minutes, @test)

This code returns:
2010-07-17 00:53:00.0000000

The six hour part is the GMT offset (which takes it to 2010-07-16 18:53:00.0000000), but this leaves a 15 day discrepancy. I think that most of this is that the day after 9/2/1752 was 9/14/1752, but this only accounts for 11 of those days. The 365.25 accounts for some also... years evenly divisible by 100, unless evenly divisibly by 400, aren't leap years. Which means in 400 years, there are 146097 days (210379680 minutes); your calculation would get 146100 days (210384000 minutes).

So, the conversion you're doing in C# looks correct to me.

You might want to consider a calendar table - list of all dates since 01/01/0001. The following code (on SQL 2008) returns the proper date/time (7/17/2010 00:53:00.0000000) for the minutes:
declare @test datetime2 = '01/01/0001'
-- See Jeff Moden's article
-- The "Numbers" or "Tally" Table: What it is and how it replaces a loop.
-- at http://www.sqlservercentral.com/articles/T-SQL/62867/.
-- NOTE! A permanent tally table will always be MUCH faster
-- than this inline one. See the above article to create your own!
;WITH
Tens (N) AS (SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL
SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL
SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0 UNION ALL SELECT 0),
Thousands(N) AS (SELECT 1 FROM Tens t1 CROSS JOIN Tens t2 CROSS JOIN Tens t3),
Millions (N) AS (SELECT 1 FROM Thousands t1 CROSS JOIN Thousands t2),
Tally (N) AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM Millions),
Dates AS (SELECT DateField = DATEADD(day, N-1, @test) FROM Tally WHERE N-1 = 1056915413/1440)
SELECT DATEADD(MINUTE, 1056915413 % 1440, DateField)
FROM Dates

Edit: Modified to add the minutes to the date in the calendar table CTE.


Wayne
Microsoft Certified Master: SQL Server 2008
If you can't explain to another person how the code that you're copying from the internet works, then DON'T USE IT on a production system! After all, you will be the one supporting it!
Links: For better assistance in answering your questions, How to ask a question, Performance Problems, Common date/time routines,
CROSS-TABS and PIVOT tables Part 1 & Part 2, Using APPLY Part 1 & Part 2, Splitting Delimited Strings
Post #949526
Posted Thursday, July 8, 2010 1:15 PM
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This conversion looks close to what you want:

select
*,
MyDateTime =
dateadd(mi,convert(bigint,a.MyTime-998799780)%convert(bigint,1440),dateadd(dd,(a.MyTime-998799780)/1440,0))
from
( -- Test Data
select MyTime = convert(bigint,1056915413) union all
select MyTime = 000001056915413+(00000000001440*2918000)



Results:

MyTime MyDateTime
--------------------- -----------------------
1056915413 2010-07-01 01:53:00.000
5258835413 9999-09-17 01:53:00.000


Edit:
Changed solution to modify time offset, and to cover the entire range of DATETIME values.
Post #949550
Posted Thursday, July 8, 2010 1:22 PM


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stevefromoz
that appears to do the trick.
can I ask how you got the minute value for 1900-01-01?
Post #949554
Posted Thursday, July 8, 2010 2:06 PM


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It may be achievable using something like todays date, but using what you gave us. You gave a starting point/constant of 1056915413 == 2010-07-01 01:53

So we're looking for [constant] - (minutes between [constant] and [1900-01-01 00:00])

which, assuming the logic is correct, could look like...

SELECT
1056915413 -- what you told me was 2010-07-01 01:53
- DATEDIFF(n, '1900-01-01 00:00', '2010-07-01 01:53') -- the date diff of that date to 1900-01-01 00:00

-- Result
998799780




Steve.
Post #949576
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