Problem with date time field

  • Hi All,

    I am new to this so need some expert guidance. In one of my datetime field data is stored in the format

    yyyy-mm-dd hh:min:sec.

    I am trying to retrieve the records between start date and end date from the user and date format is mm/dd/yyyy.

    If i write the following query

    1. select field name from tab1 where field name is >= '07/01/2008' and <= '07/03/2008' it doesnot return all records which took place on '07/03/2008' but if i write

    2.select field name from tab1 where field name is >= '07/01/2008' and <= '07/04/2008' then it returns all records..

    Can anyone suggest how to retrieve all records between two dates from query 1.

    Regards,

    Pradeep

  • pradeepkk2003 (7/6/2008)


    Hi All,

    I am new to this so need some expert guidance. In one of my datetime field data is stored in the format

    yyyy-mm-dd hh:min:sec.

    I am trying to retrieve the records between start date and end date from the user and date format is mm/dd/yyyy.

    If i write the following query

    1. select field name from tab1 where field name is >= '07/01/2008' and <= '07/03/2008' it doesnot return all records which took place on '07/03/2008' but if i write

    2.select field name from tab1 where field name is >= '07/01/2008' and <= '07/04/2008' then it returns all records..

    Can anyone suggest how to retrieve all records between two dates from query 1.

    Regards,

    Pradeep

    First, verify whether or not your column is actually stored as a datetime or a varchar\char. If it is defined as a char\varchar - you definitely need to look at changing it to a datetime.

    Now, as to your problem - what is happening is that you are experience implicit data type conversion. What that means is that when you specify '07/01/2008' - SQL Server is implicitly converting that to a datetime data type that is represented as '2008-07-01T00:00:00.000', or July 1st at midnight. When you use '07/03/2008' it is being implicitly converted to '2008-07-03T00:00:00.000'.

    BTW - this shows us that the column being compared is defined as datetime since you are getting the implicit conversion to datetime to match the column.

    The question for you is, is '2008-07-03T13:58:58.000' less than '2008-07-03T00:00:00.000'?

    As a general practice, you should always use the next day at midnight for date ranges. For example, in your query it should be:

    Select column(s)

    From table

    Where datecolumn >= '20080701'

    And datecolumn < '20080704';

    Jeffrey Williams
    “We are all faced with a series of great opportunities brilliantly disguised as impossible situations.”

    ― Charles R. Swindoll

    How to post questions to get better answers faster
    Managing Transaction Logs

  • Hi Jeff,

    Thanks for your reply. The start date and end date are selected by the user, so what if he selects 1st July and 3rd July , will your query fetches all results till 3rd July midnight or 2nd July midnight , do i hv to do + 1 for my enddate.

  • pradeepkk2003 (7/7/2008)


    Hi Jeff,

    Thanks for your reply. The start date and end date are selected by the user, so what if he selects 1st July and 3rd July , will your query fetches all results till 3rd July midnight or 2nd July midnight , do i hv to do + 1 for my enddate.

    If you specify < '20080703' then you will get all records until midnight July 2nd.

    If you want your query to include results from the last day the user selects, then you need to add one to the selected date.

  • Hello,

    When requesting a date range, one must remember the time part of the date.

    So whenever requesting a date range use code like this :

    select *

    from tablexyz

    where convert(varchar(10), start_date, 121) between '2008-01-01' and '2008-02-25'

    This convert funtion call will remove the time part and the string format 121 matches the suggested string ranges.

    Hope this helps.

    Regards,

    Terry

  • tbeadle (7/7/2008)


    Hello,

    When requesting a date range, one must remember the time part of the date.

    So whenever requesting a date range use code like this :

    select *

    from tablexyz

    where convert(varchar(10), start_date, 121) between '2008-01-01' and '2008-02-25'

    This convert funtion call will remove the time part and the string format 121 matches the suggested string ranges.

    Hope this helps.

    Regards,

    Terry

    Terry, although this will work it is not recommended. Using CONVERT on the column will eliminate the usage of any indexes on the column being converted (e.g. start_date). And, because BETWEEN is inclusive, the only reliable way to use between with dates is to do the following:

    WHERE start_date BETWEEN '2008-01-01T00:00:00.000' AND '2008-02-25T23:59:59.997'

    The above will require that you convert the input dates (if the dates are passed in as parameters to a procedure) so that you strip the time for both date parameters, and then add back into the end date parameter the time as above.

    I prefer the method of stripping the time from both parameters, adding 1 to the end date parameter and using:

    WHERE start_date >= @begin_date

    AND start_date < @end_date

    Jeffrey Williams
    “We are all faced with a series of great opportunities brilliantly disguised as impossible situations.”

    ― Charles R. Swindoll

    How to post questions to get better answers faster
    Managing Transaction Logs

  • You can do following if your start_date is of character type and you have problems comparing the date columns:

    select * from tablexyz

    where convert(datetime,convert(varchar(10), getdate(), 101)) between '01/01/2008' and '02/25/2008'

    --date format is mm/dd/yyyy

  • Hi Pradeep,

    U can try this

    where field name >= '07/01/2008' and dateadd(dd,-1,field name ) < '07/03/2008'

    regards,

    Balamurugan G

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