PRB: Varchar Output Parameter Causes "Data Truncated" Error (182386)
The information in this article applies to:
- Microsoft Visual C++, 32-bit Enterprise Edition 5.0
- Microsoft Visual C++, 32-bit Professional Edition 5.0
This article was previously published under Q182386 SYMPTOMS
When using MFC ODBC to call a Microsoft SQL Server stored procedure that
returns a CHAR or VARCHAR output parameter, the buffer intended to hold the
data returned will be Null and ODBC will return the error:
Warning: ODBC Success With Info, Data truncated
State:01004,Native:0,Origin:[Microsoft][ODBC SQL Server Driver]
CAUSE
This problem is caused by the way that parameters are bound in the RFX_Text
function. The call to SQLBindParameter appears as follows:
AFX_SQL_SYNC(::SQLBindParameter(pFX->m_hstmt, (UWORD)nField,
(SWORD)pFX->m_nFieldType, SQL_C_CHAR, (SWORD)nColumnType,
nMaxLength, nScale, pvParam, 0, plLength));
The problem is the next to the last parameter, the cbValueMax argument,
which is hard coded to 0 (zero). The cbValueMax argument specifies the
length of the buffer; it applies only to character data, not to numerics.
If the number of bytes available to return is greater than or equal to this
number, then the driver truncates it to cbValueMax-1 and null terminates it
(and throws the error above). Because the parameter is hard coded to 0, the
error will always be returned.
RESOLUTION
The resolution is to copy the RFX_Text function from Dbrfx.cpp and paste it
into your project. Give it a name, such as RFX_TextOut, and then locate the
SQLBindParameter call in question (right below the first UNICODE section).
Change the SQLBindParameter call to the following:
AFX_SQL_SYNC(::SQLBindParameter(pFX->m_hstmt, (UWORD)nField,
(SWORD)pFX->m_nFieldType, SQL_C_CHAR, (SWORD)nColumnType,
nMaxLength, nScale, pvParam, nMaxLength, plLength));
By using the nMaxLength input parameter, the new RFX_Text function allows
the driver to set up a buffer of the correct size for the text Output
parameter.
STATUS
Microsoft is researching this problem and will post new information here in
the Microsoft Knowledge Base as it becomes available.
| Modification Type: | Major | Last Reviewed: | 10/24/2003 |
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| Keywords: | kbDatabase kbprb KB182386 |
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