Re: Possible Type Conversion Defect
- From: "Angel Saenz-Badillos[MS]" <angelsa@xxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 10 Jan 2006 12:58:24 -0800
Pedro and David,
Thank you for your feedback, we have received OVERWHELMING feedback on our
"purist" coercion story and have reconsidered this feature for the final
release. One of the main reasons why we were not able to ship on November 4
as we had planned has been the tremendous ammount of work that implementing
this feature this late in the game represents.
I am happy to say that you can expect coercion to work per JDBC specs when
we ship this month.
--
Angel Saenz-Badillos [MS] DataWorks
This posting is provided "AS IS", with no warranties, and confers no
rights.Please do not send email directly to this alias.
This alias is for newsgroup purposes only.
I am now blogging: http://weblogs.asp.net/angelsb/
"Pedro Nunes" <pedronunesbr@xxxxxxxxx> wrote in message
news:1136344294.241442.283840@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Hi,
>
> I'm developing a large application using SAP Web Application Server
> with JDBC Driver Beta 2 for SQL Server 2005 and I'm getting the SAME
> problem.
> Our solution is an application developed in Visual Studio .NET 2005 and
> another developed in Java with Hibernate.
> There's any solution or I must change my strategy to don't choice SQL
> Server 2005 as default database because don't have a valid and
> compatibility JDBC driver?
>
> Thanks,
>
> Pedro
>
> David Klebanoff escreveu:
>
>> Angel, we have a very serious issue with this choice of type conversion
>> behaviour. At the moment, our application will simply not run with the
>> Beta 2
>> driver.
>>
>> Specifically we are breaking due to the lack of conversion from BIGINT to
>> int. However, I am not ruling out other type conversion issues that may
>> surface later (right now I can't run the app at all until I deal with
>> this
>> particular one).
>>
>> As you pointed out, this behaviour is inconsistent with the previous
>> Microsoft SQL Server 2000 JDBC driver. But it is also inconsistent with
>> the
>> other major drivers, namely IBM DB2, IBM DB2 z/OS, Oracle 9i and Oracle
>> 10g
>> (which incidentally, we must also support from the same codebase). All of
>> these drivers will narrow the type and throw if the value is out of range
>> or
>> unconvertable.
>>
>> I'll agree that the JDBC API specifications could be a bit more precise.
>> However, the documentation for the ResultSet class says: "For the getter
>> methods, a JDBC driver attempts to convert the underlying data to the
>> Java
>> type specified in the getter method and returns a suitable Java value.
>> The
>> JDBC specification has a table showing the allowable mappings from SQL
>> types
>> to Java types that can be used by the ResultSet getter methods. "
>> BIGINT->int
>> is shown as allowed in the JDBC specification.
>>
>> But this isn't the real point. The real point is that it is critical to
>> preserve existing behaviour. If you want to change existing behaviour,
>> particularly in a way that can break deployed software, then you need to
>> make
>> it parametrically controllable.
>>
>> Please reconsider this strategy.
>>
>> David Klebanoff
>>
>> "Angel Saenz-Badillos[MS]" wrote:
>>
>> > Thank you for your feedback, as you mention this is going to impact
>> > existing
>> > code and we are nervous to see how specific areas are affecting
>> > customers.
>> > We believe that this is the right story going forward but we may have
>> > to
>> > bend it a little for specific customer scenarios. We have already
>> > received
>> > some pushback on getObject for uniqueIdentifiers (currently returns a
>> > byte
>> > array which is how the server stores it but is not particularily
>> > usefull)
>> > and supporting getLong on a Numeric(Decimal) type. If you have any
>> > other
>> > suggestions be sure to post them here or file them as bug in the msdn
>> > product feedback site :
>> > http://lab.msdn.microsoft.com/productfeedback/default.aspx
>> >
>> > There is still time to integrate customer feedback into this data
>> > coercion
>> > story, but it is running out fast.
>> >
>> > --
>> > Angel Saenz-Badillos [MS] DataWorks
>> > This posting is provided "AS IS", with no warranties, and confers no
>> > rights.Please do not send email directly to this alias.
>> > This alias is for newsgroup purposes only.
>> > I am now blogging: http://weblogs.asp.net/angelsb/
>> >
>> >
>> >
>> >
>> > "Eric Molitor" <EricMolitor@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>> > news:3D094877-F2AC-4E91-9FDB-324FBB29BCD5@xxxxxxxxxxxxxxxx
>> > > Right, I dug into this and was able to solve the problems both with
>> > > conversions and by fixing some bad practices in our SQL...
>> > >
>> > > In several places after executing an insert we would simply...
>> > >
>> > > select @@IDENTITY as identityValue
>> > >
>> > > and then retrieve the value from the result set in java. Obviously we
>> > > should
>> > > have been using SCOPE_IDENTITY() for one but also we should have been
>> > > using
>> > > an out put parameter...
>> > >
>> > > So the proc becomes
>> > >
>> > > CREATE PROCEDURE spTestProc
>> > > (
>> > > @username varchar(8),
>> > > @firstname varchar(255),
>> > > @lastname varchar(255),
>> > > @UserID int OUTPUT
>> > > ) as
>> > >
>> > > INSERT INTO User (username, firstname, lastname)
>> > > VALUES (@username, @firstname, @lastname)
>> > >
>> > > SELECT @UserID = SCOPE_IDENTITY()
>> > >
>> > > and in the code we just fetch the value as an output parameter...
>> > >
>> > > So once all of this shakes out I do think it will be a positive
>> > > change,
>> > > however I'm sure lots of people will have some SQL and Java to
>> > > cleanup.
>> > >
>> > > Cheers,
>> > > Eric
>> > >
>> > >
>> > >
>> > > "Angel Saenz-Badillos[MS]" wrote:
>> > >
>> > >> We wanted to be very explicit with our data coercion story and as
>> > >> far as
>> > >> we
>> > >> have been able we are not going to allow getting a type from the
>> > >> server
>> > >> that
>> > >> would require a downcast to the client and possible loss of data.
>> > >> This
>> > >> strategy has the advantage of high predictability with limited
>> > >> chance of
>> > >> data loss, but it is very restrictive.
>> > >>
>> > >> Quite frankly I was expecting to see a lot more people commenting on
>> > >> these.
>> > >> In your case 108 is of type NUMERIC, a 38bit precission decimal and
>> > >> you
>> > >> are
>> > >> trying to shove it into an INTEGER. Type 38 is an INTEGER which does
>> > >> not
>> > >> fit
>> > >> on a SMALLINT.
>> > >>
>> > >> We only have two choices here that don't involve data loss
>> > >> (something we
>> > >> are
>> > >> definitelly not going to allow),
>> > >> 1) We can NEVER allow a conversion from a type if _the type you are
>> > >> trying
>> > >> to convert_ does not fit into the type that you are trying to coerce
>> > >> it
>> > >> into. This is the behavior that we have opted for in the 2005 JDBC
>> > >> driver.
>> > >>
>> > >> 2) We can allow a conversion from a type that does not fit into the
>> > >> coreced
>> > >> type _only_ when the current value that you are asking for can be
>> > >> coerced
>> > >> into the type that you are asking for. This is the behavior of the
>> > >> 2000
>> > >> JDBC
>> > >> driver.
>> > >>
>> > >> Let's say that you have a NUMERIC column that has a value of 5, when
>> > >> you
>> > >> call getInt on this we will throw an exception if following (1) but
>> > >> the
>> > >> coercion will work on a driver that supports (2) since 5 does fit
>> > >> into an
>> > >> INTEGER type. When you have a driver that provides the (1)
>> > >> functionality
>> > >> you
>> > >> will realize the first time you run your code that a NUMERIC column
>> > >> will
>> > >> not
>> > >> always fit into an int and change your code accordingly. When
>> > >> working
>> > >> with a
>> > >> driver of the (2) type you will test and deploy your application
>> > >> with
>> > >> getInt. When the value of the NUMERIC column goes over what an
>> > >> INTEGER
>> > >> can
>> > >> handle you will get a runtime exception and you will have to go
>> > >> service
>> > >> your
>> > >> deployed application.
>> > >>
>> > >> We realize that it can be inconvenient to have this kind of issues
>> > >> surfaced
>> > >> early, but we feel it is better to let you know up front about
>> > >> possible
>> > >> data
>> > >> coercion issues, if you really wanted to get an integer from the
>> > >> server
>> > >> you
>> > >> would have defined your table accordingly, or you could have
>> > >> requested an
>> > >> integer in your query with the CONVERT function.
>> > >>
>> > >> I think that this is going to be a common question, I am going to
>> > >> convert
>> > >> this post into a blog and post it into the
>> > >> http://blogs.msdn.com/dataaccess/
>> > >> with a complete data coercion table to help make this design
>> > >> clearer, of
>> > >> course comments/suggestions are welcome.
>> > >> --
>> > >> Angel Saenz-Badillos [MS] DataWorks
>> > >> This posting is provided "AS IS", with no warranties, and confers no
>> > >> rights.Please do not send email directly to this alias.
>> > >> This alias is for newsgroup purposes only.
>> > >> I am now blogging: http://weblogs.asp.net/angelsb/
>> > >>
>> > >>
>> > >>
>> > >>
>> > >> "Eric Molitor" <EricMolitor@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
>> > >> message
>> > >> news:237EAB6D-63BA-4DB2-AB0C-7EB8D98B3E2D@xxxxxxxxxxxxxxxx
>> > >> > Seem to be getting these consistantly in certain portions of our
>> > >> > application.
>> > >> > Works fine with the older JDBC driver (2000) but under the 2005
>> > >> > driver
>> > >> > we
>> > >> > see....
>> > >> >
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerException: Unsupported
>> > >> > conversion
>> > >> > from
>> > >> > 108 to INTEGER
>> > >> > at
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerStatement.getRowsetField(Unknown
>> > >> > Source)
>> > >> > at com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown
>> > >> > Source)
>> > >> > at com.microsoft.sqlserver.jdbc.SQLServerResultSet.getInt(Unknown
>> > >> > Source)
>> > >> >
>> > >> > and
>> > >> >
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerException: Unsupported
>> > >> > conversion
>> > >> > from
>> > >> > 38 to SMALLINT
>> > >> > at
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerStatement.getRowsetField(Unknown
>> > >> > Source)
>> > >> > at
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerResultSet.getShort(Unknown
>> > >> > Source)
>> > >> > at
>> > >> > com.microsoft.sqlserver.jdbc.SQLServerResultSet.getShort(Unknown
>> > >> > Source)
>> > >> >
>> > >> > I'm looking at the SQL and the code but I'd think 38 is a valid
>> > >> > SMALLINT
>> > >> > and
>> > >> > that 108 is a valid INTEGER.
>> > >> >
>> > >> >
>> > >>
>> > >>
>> > >>
>> >
>> >
>> >
>
.
- References:
- Re: Possible Type Conversion Defect
- From: Pedro Nunes
- Re: Possible Type Conversion Defect
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