Conversion from VT_DECIMAL TO VT

hfann

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Jul 31, 2005, 10:33:12 PM7/31/05

to

Hi,

I have a C++ program that creates records in a MSDE2000a database. I use a
stored procedure to create the record and it returns an identity value. The
returned value is stored in a BIGINT output parameter.

CREATE PROCEDURE dbo.AddEntry
...,
@pEntryID BIGINT = NULL OUTPUT
AS
...

In C++ code:

_ParameterPtr Parm =
pCommand->CreateParameter(L"@pEntryID",adBigInt,adParamOutput,9);
pCommand->Parameters->Append(Parm);
pCommand->Execute(0,0,adCmdStoredProc);
...
__int64 iRecID = 0;
try {
_variant_t Val = Parm->Value;
iRecID = Val;
} catch(_com_error &e) {
_bstr_t sMsg = e.Description();
return -1;
}

The program runs fine on an English version of Windows XP. On a German
version of Windows 2000, the conversion (iRec = Val;) always fails with
0x80020008 COM error. In both cases, the database is created with an English
version of MSDE2000a.

Why does a BIGINT parameter becomes a VT_DECIMAL variant? Why does the
conversion failed? Did I code something wrong? What is the workaround?

Thanks,
--
Herbert
Fann Software
http://www.fannsoftware.com

Steven Cheng[MSFT]

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Aug 1, 2005, 6:56:05 AM8/1/05

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Hi Herbert,

Welcome to MSDN newsgroup.
Regarding on the Type Converting problem met in accessing database through
ado, based on the code you provided, here are some of our suggestion:

Since this is likely a environment specific problem, currently what we can
do is simply do some further tests. for the _variant_t , it has a
"ChangeType" function which can help explicitly cast the currently value in
the _variant_t instance into our specified type. I suggest you try using
this method to explicitly cast the returned value before assign it to the
_int64(long long type). Just as:

_variant_t Val = Parm->Value;

//call ChangeType here
iRecID = Val;

Please feel free to post here if there is any other findings. Thanks,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

hfann

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Aug 1, 2005, 2:57:15 PM8/1/05

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Hi Steven,

I have tried

iRecID = (__int64)Val;

or

Val.ChangeType(VT_I8);
iRecID = Val;

Both failed on a fresh German Windows 2000 Pro with SP4 system.

Why does a BIGINT parameter becomes a VT_DECIMAL variant? Should it create a
VT_I8 variant in the first place?

Thanks,

--
Herbert
Fann Software
http://www.fannsoftware.com

Kevin Yu [MSFT]

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Aug 2, 2005, 3:16:33 AM8/2/05

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Hi Herbert,

Based on my research, this might be a known problem in earlier version of
MDAC. Since you're using Windows 2000 sp4, I suggest you apply MDAC 2.8
sp1. You can download it from the following link and select German in the
language selection.

http://www.microsoft.com/downloads/details.aspx?FamilyID=78cac895-efc2-4f8e-
a9e0-3a1afbd5922e&DisplayLang=en

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

hfann

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Aug 2, 2005, 11:59:01 AM8/2/05

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Hi,

After I installed a German version MDAC 2.8 SP1, the conversion still failed
with 0x80020008 error when I debuged it in VS.NET 2003.

Thanks,
--
Herbert
Fann Software
http://www.fannsoftware.com

Kevin Yu [MSFT]

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Aug 3, 2005, 1:36:25 AM8/3/05

to

Hi Herbert,

In this case, I suggest you contact Microsoft PSS for this issue, since
they might have resource to test this issue. You can get the contact
information from the following link

http://support.microsoft.com/default.aspx?scid=fh;EN-US;OfferProPhone

Conversion from VT_DECIMAL TO VT_I8 failed

hfann

Steven Cheng[MSFT]

hfann

Kevin Yu [MSFT]

hfann

Kevin Yu [MSFT]