Datetime in where clause

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终归单人心
终归单人心 2020-12-13 08:15

How can I select 12/20/2008 in where clause of sql?

The server is SQL server 2005.

select * from tblErrorLog
where errorDate = \'12/20/2         


        
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  • 2020-12-13 08:49

    You don't say which database you are using but in MS SQL Server it would be

    WHERE DateField = {d '2008-12-20'}
    

    If it is a timestamp field then you'll need a range:

    WHERE DateField BETWEEN {ts '2008-12-20 00:00:00'} AND {ts '2008-12-20 23:59:59'}
    
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  • 2020-12-13 08:50

    Use a convert function to get all entries for a particular day.

    Select * from tblErrorLog where convert(date,errorDate,101) = '12/20/2008'
    

    See CAST and CONVERT for more info

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  • 2020-12-13 08:54

    Assuming we're talking SQL Server DateTime

    Note: BETWEEN includes both ends of the range, so technically this pattern will be wrong:

    errorDate BETWEEN '12/20/2008' AND '12/21/2008'
    

    My preferred method for a time range like that is:

    '20081220' <= errorDate AND errordate < '20081221'
    

    Works with common indexes (range scan, SARGable, functionless) and correctly clips off midnight of the next day, without relying on SQL Server's time granularity (e.g. 23:59:59.997)

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  • 2020-12-13 08:58
    WHERE datetime_column >= '20081220 00:00:00.000'
      AND datetime_column < '20081221 00:00:00.000'
    
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  • 2020-12-13 09:01
    select * from tblErrorLog
    where errorDate BETWEEN '12/20/2008' AND DATEADD(DAY, 1, '12/20/2008')
    
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  • 2020-12-13 09:10

    First of all, I'd recommend using the ISO-8601 standard format for date/time - it works regardless of the language and regional settings on your SQL Server. ISO-8601 is the YYYYMMDD format - no spaces, no dashes - just the data:

    select * from tblErrorLog
    where errorDate = '20081220'
    

    Second of all, you need to be aware that SQL Server 2005 DATETIME always includes a time. If you check for exact match with just the date part, you'll get only rows that match with a time of 0:00:00 - nothing else.

    You can either use any of the recommend range queries mentioned, or in SQL Server 2008, you could use the DATE only date time - or you could do a check something like:

    select * from tblErrorLog
    where DAY(errorDate) = 20 AND MONTH(errorDate) = 12 AND YEAR(errorDate) = 2008
    

    Whichever works best for you.

    If you need to do this query often, you could either try to normalize the DATETIME to include only the date, or you could add computed columns for DAY, MONTH and YEAR:

    ALTER TABLE tblErrorLog
       ADD ErrorDay AS DAY(ErrorDate) PERSISTED
    ALTER TABLE tblErrorLog
       ADD ErrorMonth AS MONTH(ErrorDate) PERSISTED
    ALTER TABLE tblErrorLog
       ADD ErrorYear AS YEAR(ErrorDate) PERSISTED
    

    and then you could query more easily:

    select * from tblErrorLog
    where ErrorMonth = 5 AND ErrorYear = 2009
    

    and so forth. Since those fields are computed and PERSISTED, they're always up to date and always current, and since they're peristed, you can even index them if needed.

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