Q168447: PRB: DAO SetParamValue Limited to 255 Characters
Article: Q168447
Product(s): Microsoft C Compiler
Version(s): 4.0 4.1 4.2 5.0 6.0
Operating System(s):
Keyword(s): kbcode kberrmsg kbDAOsearch kbDatabase kbMFC kbVC kbVC400 kbVC410 kbVC420 kbVC500 kbVC6
Last Modified: 17-JUL-2001
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The information in this article applies to:
- The Microsoft Foundation Classes (MFC), included with:
- Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1
- Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2
- Microsoft Visual C++, 32-bit Professional Edition, version 4.2
- Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0
- Microsoft Visual C++, 32-bit Professional Edition, version 5.0
- Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0
- Microsoft Visual C++, 32-bit Professional Edition, version 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
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SYMPTOMS
========
The execution of a query following a call to CDaoQueryDef::SetParamValue()
results in an error similar to the following:
DAO Call Failed.
m_pDAOQueryDef->Execute(COleVariant((long)nOptions))
In file daocore.cpp on line 2880
scode = 800A0BC9
Error Code = 3017
Source = DAO.QueryDef
Description = The size of a field is too long.
CAUSE
=====
Parameter values are limited to 255 characters.
RESOLUTION
==========
Do not call SetParamValue with a value that contains more than 255 characters.
If you need to update or insert a record that does contain long data, use a
recordset rather than a querydef.
MORE INFORMATION
================
DAO and the Jet Engine restrict parameter values to 255 characters or less; this
is not a limitation of the MFC DAO classes.
Sample Code
-----------
/* Compile options needed: none
*/
CDaoDatabase db;
CDaoQueryDef query( &db );
int idx;
CByteArray blob;
const int SIZE = 255; // Execute will succeed if 255, fail if 256
try
{
db.Open( "C:\\DB1.mdb" );
query.Open( "Query1" );
query.SetParamValue( "theID", COleVariant( (long)1, VT_I4 ) );
blob.SetSize( SIZE );
for( idx = 0; idx < SIZE; ++idx )
blob.SetAt( idx, (BYTE)idx );
query.SetParamValue( "theBlob", COleVariant( blob ) );
query.Execute();
}
catch( CDaoException* e )
{
AfxMessageBox( e->m_pErrorInfo->m_strDescription,
MB_ICONEXCLAMATION );
e->Delete();
}
query.Close();
db.Close();
Additional query words:
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Keywords : kbcode kberrmsg kbDAOsearch kbDatabase kbMFC kbVC kbVC400 kbVC410 kbVC420 kbVC500 kbVC600 kbprb
Technology : kbAudDeveloper kbMFC
Version : 4.0 4.1 4.2 5.0 6.0
Issue type : kbprb
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