DATEPART acting differently under SQL 2005 in WHERE clause

  • I am in the process of upgrading a few databases from 2000 to 2005 at the compnay I work for and came across an issue I have not seen with DATEPART before. Anyone aware of this, is it intentional or is there a patch I missed to resolve it? It only seems to happen with derived tables which worked fine under SQL 2000.

    first this works fine using DATEPART

    SELECT

    Dates,

    CASE WHEN DATEPART(dw,Dates) IN (2,3,4,5,6) THEN 1 ELSE 0 END

    FROM

    (

    SELECT

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) Dates

    FROM

    (

    SELECT 1 nMonth

    UNION

    SELECT 2 nMonth

    UNION

    SELECT 3 nMonth

    UNION

    SELECT 4 nMonth

    UNION

    SELECT 5 nMonth

    UNION

    SELECT 6 nMonth

    UNION

    SELECT 7 nMonth

    UNION

    SELECT 8 nMonth

    UNION

    SELECT 9 nMonth

    UNION

    SELECT 10 nMonth

    UNION

    SELECT 11 nMonth

    UNION

    SELECT 12 nMonth

    ) tMonths

    cross join

    (

    SELECT 1 nDay

    UNION

    SELECT 2 nDay

    UNION

    SELECT 3 nDay

    UNION

    SELECT 4 nDay

    UNION

    SELECT 5 nDay

    UNION

    SELECT 6 nDay

    UNION

    SELECT 7 nDay

    UNION

    SELECT 8 nDay

    UNION

    SELECT 9 nDay

    UNION

    SELECT 10 nDay

    UNION

    SELECT 11 nDay

    UNION

    SELECT 12 nDay

    UNION

    SELECT 13 nDay

    UNION

    SELECT 14 nDay

    UNION

    SELECT 15 nDay

    UNION

    SELECT 16 nDay

    UNION

    SELECT 17 nDay

    UNION

    SELECT 18 nDay

    UNION

    SELECT 19 nDay

    UNION

    SELECT 20 nDay

    UNION

    SELECT 21 nDay

    UNION

    SELECT 22 nDay

    UNION

    SELECT 23 nDay

    UNION

    SELECT 24 nDay

    UNION

    SELECT 25 nDay

    UNION

    SELECT 26 nDay

    UNION

    SELECT 27 nDay

    UNION

    SELECT 28 nDay

    UNION

    SELECT 29 nDay

    UNION

    SELECT 30 nDay

    UNION

    SELECT 31 nDay

    ) tDays

    cross join

    (SELECT 2008 AS nYear) nYears

    where

    IsDate(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) = 1 AND

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) BETWEEN '20080501' AND '20080506'

    ) tBase

    ORDER BY

    Dates ASC

    However placing the same thing in the WHERE cluse breaks with error

    "The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value."

    SELECT

    Dates

    FROM

    (

    SELECT

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) Dates

    FROM

    (

    SELECT 1 nMonth

    UNION

    SELECT 2 nMonth

    UNION

    SELECT 3 nMonth

    UNION

    SELECT 4 nMonth

    UNION

    SELECT 5 nMonth

    UNION

    SELECT 6 nMonth

    UNION

    SELECT 7 nMonth

    UNION

    SELECT 8 nMonth

    UNION

    SELECT 9 nMonth

    UNION

    SELECT 10 nMonth

    UNION

    SELECT 11 nMonth

    UNION

    SELECT 12 nMonth

    ) tMonths

    cross join

    (

    SELECT 1 nDay

    UNION

    SELECT 2 nDay

    UNION

    SELECT 3 nDay

    UNION

    SELECT 4 nDay

    UNION

    SELECT 5 nDay

    UNION

    SELECT 6 nDay

    UNION

    SELECT 7 nDay

    UNION

    SELECT 8 nDay

    UNION

    SELECT 9 nDay

    UNION

    SELECT 10 nDay

    UNION

    SELECT 11 nDay

    UNION

    SELECT 12 nDay

    UNION

    SELECT 13 nDay

    UNION

    SELECT 14 nDay

    UNION

    SELECT 15 nDay

    UNION

    SELECT 16 nDay

    UNION

    SELECT 17 nDay

    UNION

    SELECT 18 nDay

    UNION

    SELECT 19 nDay

    UNION

    SELECT 20 nDay

    UNION

    SELECT 21 nDay

    UNION

    SELECT 22 nDay

    UNION

    SELECT 23 nDay

    UNION

    SELECT 24 nDay

    UNION

    SELECT 25 nDay

    UNION

    SELECT 26 nDay

    UNION

    SELECT 27 nDay

    UNION

    SELECT 28 nDay

    UNION

    SELECT 29 nDay

    UNION

    SELECT 30 nDay

    UNION

    SELECT 31 nDay

    ) tDays

    cross join

    (SELECT 2008 AS nYear) nYears

    where

    IsDate(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) = 1 AND

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) BETWEEN '20080501' AND '20080506'

    ) tBase

    WHERE

    (CASE WHEN DATEPART(dw,Dates) IN (2, 3, 4, 5, 6) THEN 1 ELSE 0 END) = 1

    ORDER BY

    Dates ASC

    I have not tried this against 2008 as of yet and there is no corporate plan to transition to 2008 yet.

  • Sorry additional note. This too oddly enough fails with the same error.

    select * from

    (

    SELECT

    Dates,

    (CASE WHEN DATEPART(dw,Dates) IN (2,3,4,5,6) THEN 1 ELSE 0 END) DOFW

    FROM

    (

    SELECT

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) Dates

    FROM

    (

    SELECT 1 nMonth

    UNION

    SELECT 2 nMonth

    UNION

    SELECT 3 nMonth

    UNION

    SELECT 4 nMonth

    UNION

    SELECT 5 nMonth

    UNION

    SELECT 6 nMonth

    UNION

    SELECT 7 nMonth

    UNION

    SELECT 8 nMonth

    UNION

    SELECT 9 nMonth

    UNION

    SELECT 10 nMonth

    UNION

    SELECT 11 nMonth

    UNION

    SELECT 12 nMonth

    ) tMonths

    cross join

    (

    SELECT 1 nDay

    UNION

    SELECT 2 nDay

    UNION

    SELECT 3 nDay

    UNION

    SELECT 4 nDay

    UNION

    SELECT 5 nDay

    UNION

    SELECT 6 nDay

    UNION

    SELECT 7 nDay

    UNION

    SELECT 8 nDay

    UNION

    SELECT 9 nDay

    UNION

    SELECT 10 nDay

    UNION

    SELECT 11 nDay

    UNION

    SELECT 12 nDay

    UNION

    SELECT 13 nDay

    UNION

    SELECT 14 nDay

    UNION

    SELECT 15 nDay

    UNION

    SELECT 16 nDay

    UNION

    SELECT 17 nDay

    UNION

    SELECT 18 nDay

    UNION

    SELECT 19 nDay

    UNION

    SELECT 20 nDay

    UNION

    SELECT 21 nDay

    UNION

    SELECT 22 nDay

    UNION

    SELECT 23 nDay

    UNION

    SELECT 24 nDay

    UNION

    SELECT 25 nDay

    UNION

    SELECT 26 nDay

    UNION

    SELECT 27 nDay

    UNION

    SELECT 28 nDay

    UNION

    SELECT 29 nDay

    UNION

    SELECT 30 nDay

    UNION

    SELECT 31 nDay

    ) tDays

    cross join

    (SELECT 2008 AS nYear) nYears

    where

    IsDate(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) = 1 AND

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) BETWEEN '20080501' AND '20080506'

    ) tBase

    ) X

    WHERE

    DOFW = 1

    ORDER BY

    Dates ASC

    Subquery provides 1 and 0 in DOFW filed somewhere SQL 2005 just doesn't like this.

  • OK found a workable solution by using a table-valued funtion to handle the dates part and substituting it out in the code. Which I can see how it works as the function returns a table variable and is not derived. But I find nothing about this DATEPART changing or how derived tables are managed. Does anyone know where this change in behavior is documented?

    CREATE FUNCTION dbo.DatesInRange(@Start datetime, @Stop datetime)

    RETURNS @Dates TABLE (Dates datetime)

    AS

    BEGIN

    INSERT INTO @Dates (DATES)

    SELECT

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) Dates

    FROM

    (

    SELECT 1 nMonth

    UNION

    SELECT 2 nMonth

    UNION

    SELECT 3 nMonth

    UNION

    SELECT 4 nMonth

    UNION

    SELECT 5 nMonth

    UNION

    SELECT 6 nMonth

    UNION

    SELECT 7 nMonth

    UNION

    SELECT 8 nMonth

    UNION

    SELECT 9 nMonth

    UNION

    SELECT 10 nMonth

    UNION

    SELECT 11 nMonth

    UNION

    SELECT 12 nMonth

    ) tMonths

    cross join

    (

    SELECT 1 nDay

    UNION

    SELECT 2 nDay

    UNION

    SELECT 3 nDay

    UNION

    SELECT 4 nDay

    UNION

    SELECT 5 nDay

    UNION

    SELECT 6 nDay

    UNION

    SELECT 7 nDay

    UNION

    SELECT 8 nDay

    UNION

    SELECT 9 nDay

    UNION

    SELECT 10 nDay

    UNION

    SELECT 11 nDay

    UNION

    SELECT 12 nDay

    UNION

    SELECT 13 nDay

    UNION

    SELECT 14 nDay

    UNION

    SELECT 15 nDay

    UNION

    SELECT 16 nDay

    UNION

    SELECT 17 nDay

    UNION

    SELECT 18 nDay

    UNION

    SELECT 19 nDay

    UNION

    SELECT 20 nDay

    UNION

    SELECT 21 nDay

    UNION

    SELECT 22 nDay

    UNION

    SELECT 23 nDay

    UNION

    SELECT 24 nDay

    UNION

    SELECT 25 nDay

    UNION

    SELECT 26 nDay

    UNION

    SELECT 27 nDay

    UNION

    SELECT 28 nDay

    UNION

    SELECT 29 nDay

    UNION

    SELECT 30 nDay

    UNION

    SELECT 31 nDay

    ) tDays

    cross join

    (SELECT 2008 AS nYear) nYears

    where

    IsDate(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) = 1 AND

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) BETWEEN @Start AND @Stop

    RETURN

    END

  • [font="Verdana"]One issue I can see: not all months have the same number of days (31st of February, anyone?). Why not encode the first and last day with the month list? Then you could add a between to the where clause to filter out invalid days. The issue then arises with leap years.

    You might be better off just counting year days, rather than months and days, and use datepart() and datename() to pull out the appropriate bits.

    BTW, get in the habit of using UNION ALL, not UNION (unless you specifically need the filtering of UNION.)

    [/font]

  • This is odd. Somebody smarter than me will have to give you the answer on this one. If you look at the

    Estimated Execution Plan, it looks like the entire table is built and then the next to last operation is a

    Compute Scalar that is applying ALL the criteria in one step, but unfortunately because of this the IsDate is

    not applied in time.

    I'm attaching the Estimated Execution Plan from my 2005 SP3 box.

    One other note, could you format the code so it is a little narrower, it doesn't even fit in my 22" widescreen

    without a horizontal scroll bar.

    Jack Corbett
    Consultant - Straight Path Solutions
    Check out these links on how to get faster and more accurate answers:
    Forum Etiquette: How to post data/code on a forum to get the best help
    Need an Answer? Actually, No ... You Need a Question

  • [font="Verdana"]When you use an expression in the form x AND y, SQL Server can "lazy evaluate" by saying "if the first part is false, I don't need to even look at the second part." This is what you are relying.

    However, there's no guarantee that SQL Server won't recorder, as x AND y is equivalent to y AND x. So it may be doing that to pull out common sub-expressions within the two parts of the code.

    I think it would be better just to generate valid dates to start with.

    [/font]

  • Bruce W Cassidy (3/9/2009)


    [font="Verdana"]One issue I can see: not all months have the same number of days (31st of February, anyone?). Why not encode the first and last day with the month list? Then you could add a between to the where clause to filter out invalid days. The issue then arises with leap years.

    You might be better off just counting year days, rather than months and days, and use datepart() and datename() to pull out the appropriate bits.

    BTW, get in the habit of using UNION ALL, not UNION (unless you specifically need the filtering of UNION.)

    [/font]

    Written a long time ago on SQL 7 so has been that way thru 2000. The IsDate funtion check removes any invalid dates before I do my processing so leap years are covered. Will consider changing UNION to UNION ALL to avoid the filtering step as suggested, thanks.

  • One other note, could you format the code so it is a little narrower, it doesn't even fit in my 22" widescreen

    without a horizontal scroll bar.

    Fixed formatting.

  • Jack Corbett (3/9/2009)


    This is odd. Somebody smarter than me will have to give you the answer on this one. If you look at the

    Estimated Execution Plan, it looks like the entire table is built and then the next to last operation is a

    Compute Scalar that is applying ALL the criteria in one step, but unfortunately because of this the IsDate is

    not applied in time.

    Looks like you have found the issue. I removed 29-31 as possible day options for the month and ran without an issue. However them does seem an odd behavior since the where inside there should be applied for the table to be derived correctly. Even when I wrap that into another derived table the issue seems to be DATEPART is applied before the IsDate. I do have a workaround but will submit to MS for more feedback. Thanks

  • Antares686 (3/10/2009)


    Jack Corbett (3/9/2009)


    This is odd. Somebody smarter than me will have to give you the answer on this one. If you look at the

    Estimated Execution Plan, it looks like the entire table is built and then the next to last operation is a

    Compute Scalar that is applying ALL the criteria in one step, but unfortunately because of this the IsDate is

    not applied in time.

    Looks like you have found the issue. I removed 29-31 as possible day options for the month and ran without an issue. However them does seem an odd behavior since the where inside there should be applied for the table to be derived correctly. Even when I wrap that into another derived table the issue seems to be DATEPART is applied before the IsDate. I do have a workaround but will submit to MS for more feedback. Thanks

    It appears that the Query Optimizer is deciding that it is faster to generate all the rows for the derived table and then apply the filters. I even tried putting the outer derived table, tBase, in a CTE to see if that would force the order and it did not.

    I just tried it against a 2008 install and the result is the same as 2005. The query plan still does the derived table(s) and then applies the filters.

    Jack Corbett
    Consultant - Straight Path Solutions
    Check out these links on how to get faster and more accurate answers:
    Forum Etiquette: How to post data/code on a forum to get the best help
    Need an Answer? Actually, No ... You Need a Question

  • please confirm that the purpose of the function is to return a table of dates between a given StartDate and EndDate inclusively, ie if StartDate were 2009-01-01 and EndDate were 2009-02-01, the dates resturned would be from 2009-01-01 through 2009-02-01.

  • This change to the inner WHERE clause will fix your problem. Conditions in a CASE statement are evaluated in order, so only values that pass the ISDATE checks will get to the date range check where your code is failing.

    where

    case

    when

    IsDate (

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) is null

    then 0

    when

    IsDate (

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    ) <> 1

    then 0

    when not

    cast(

    cast(nYear as varchar(4)) +

    right('0' + cast(nMonth as varchar(2)),2) +

    right('0' + cast(nDay as varchar(2)),2)

    as datetime) BETWEEN '20080101' AND '20081231'

    then 0

    else 1

    end = 1

  • Here is another way to generate the dates you are generating.

    CREATE FUNCTION dbo.DatesInRange(@StartDate datetime, @StopDate datetime)

    RETURNS TABLE

    AS

    return

    with

    a1 as (select 1 as N union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1 union all

    select 1),

    a2 as (select

    1 as N

    from

    a1 as a

    cross join a1 as b),

    a3 as (select

    1 as N

    from

    a2 as a

    cross join a2 as b),

    a4 as (select

    1 as N

    from

    a3 as a

    cross join a2 as b),

    Tally as (select

    row_number() over (order by N) as N

    from

    a4)

    select top (datediff(dd, @StartDate, @StopDate) + 1)

    dateadd(dd, N - 1, @StartDate) as Dates

    from

    Tally;

    go

    select * from dbo.DatesInRange('2008-01-01','2008-12-31');

    go

    DROP FUNCTION dbo.DatesInRange;

    go

  • Lynn Pettis (3/10/2009)


    please confirm that the purpose of the function is to return a table of dates between a given StartDate and EndDate inclusively, ie if StartDate were 2009-01-01 and EndDate were 2009-02-01, the dates resturned would be from 2009-01-01 through 2009-02-01.

    Yes inclusively, which works in 2000 and works using the User Defined Function to create the output.

  • I think you will find that the SQL Server 2005 version of the UDF I wrote will work just as well. It may even be more efficient as I have written it as an in-line function instead of as a multi-statement TVF as you had originally. The only way to know for sure is to test it.

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