ODBC MFC CRecordset error at runtime

[rdg2cig]

I am trying to add access to a database (currently extracted into MS Access 97 during development) into an existing MFC application that did not originally include database support. I have registered the database as &quot;RAMS&quot; through the ODBC utility on the Windows Control Pnnel. I used ClassWizard to extend the CRecordset class as CCuHdrSet and configured within the wizard to my RAMS database and one table within it CuHdr. I included <afxdb.h> in the CuHdrSet.h and my application document's .cpp file, Guy3Doc.cpp. I have created the following function to retrieve a record set which compiles fine but crashes at runtime. I get a message box on my screen when I attempt to open the CRecordset derived object (CCuHdrSet) that displays the message &quot;failed to create empty document&quot;. When the OK button on the message dialog is clicked, the application exits. If I comment out the hdrSet.Open(....) statement, the application does not terminate and the message dialog does not appear. Clearly I am doing something wrong here but I have not been able to determine my error. I need to use the recordset to obtain results of the query but haven't gotten there yet as I can't get past this error. The code snippet is provided below. If you can help, I would greatly appreciate it.


void CGuy3Doc:oQuery(void){
CDatabase m_Database;
if(!m_Database.Open(NULL, FALSE, TRUE, &quot;ODBC;DSN=RAMS&quot){
AfxMessageBox(&quot;Failed to open the database connection.&quot;
}
CCuHdrSet hdrSet(&m_Database);
hdrSet.m_strFilter = &quot;&quot;;
// the following statement is all on a single line
// in my actual program.
if(!hdrSet.Open(AFX_DB_USE_DEFAULT_TYPE, &quot;SELECT [TITLE] FROM [TIDCUHDR] WHERE [COMPATIBLE_UNIT] = 'S0440'&quot || hdrSet.IsEOF())
{
AfxMessageBox(&quot;Cannot find records.&quot;
}
// add in use of recordset here
hdrSet.Close();
m_Database.Close();
}

 

[Cagliostro]

Can you say, what error do you get? Check it with CDBException and CDBErrorInfo. John Fill

ivfmd@mail.md

 

[rdg2cig]

I changed the code as shown below to include a try/catch block for the CDBException object. The message returned was &quot;invalid descriptor index&quot;. The program did not automatically terminate with the inclusion of the exception handler. I have not used try/catch blocks in C++ before so hopefully I did it correctly.

// public function to perform database retrieval of cost data
void CGuy3Doc:oQuery(void){
try{CDatabase m_Database;
if(!m_Database.Open(NULL, FALSE, TRUE, &quot;ODBC;DSN=RAMS&quot){
AfxMessageBox(&quot;Failed to open the database connection.&quot;
}
CCuHdrSet hdrSet(&m_Database);
hdrSet.m_strFilter = &quot;&quot;;
// next statement is all on one line in actual program
if(!hdrSet.Open(AFX_DB_USE_DEFAULT_TYPE, &quot;SELECT [TITLE] FROM [TIDCUHDR] WHERE [COMPATIBLE_UNIT] = 'S0440'&quot || hdrSet.IsEOF())
{
AfxMessageBox(&quot;Cannot find records.&quot;
}

hdrSet.Close();
m_Database.Close();
}
catch(CDBException *e){
AfxMessageBox(e->m_strError);
}
}

 

[Cagliostro]

How about:
catch(CDBException e){
AfxMessageBox(e.m_strError);
}?
John Fill

ivfmd@mail.md

 

[IonelBurtan]

I am almost sure that your error comes from the statement:

if(!hdrSet.Open(AFX_DB_USE_DEFAULT_TYPE, &quot;SELECT [TITLE] FROM [TIDCUHDR] WHERE [COMPATIBLE_UNIT] = 'S0440'&quot || hdrSet.IsEOF())

I don't understand what you meant with that but I think you are trying to call a method (IeEOF()) that is called before the recordset is opened and therefore crushes.
Anyway the second parameter should be an SQL String or CALL not a || with a method call.

Hopefully I'm right,

s-)

Blessed is he who in the name of justice and good will, shepards the week through the valley of darknees...

http://www20.brinkster.com/ionelb

 

[rdg2cig]

I tried what BurtanI suggested and removed the &quot;|| hdrSet.IsEOF()&quot; from within the recordset open command but I still received the identical &quot;invalid descriptor index&quot; error.

The try/catch works fine. I changed the way I open the CRecordset derived object and can get a valid recordset back without throwing an exception. However, the filtering method seems to only allow a single value where clause (i.e. &quot;[compatible_unit]='S0440'&quot; but not &quot;[compatible_unit in ('S0440', 'S0460')&quot;. I need to be able to retrieve records based on multiple where clause values.

void CGuy3Doc:oQuery(void){
try{CDatabase m_Database;
if(!m_Database.Open(NULL, FALSE, TRUE, &quot;ODBC;DSN=RAMS&quot){
AfxMessageBox(&quot;Failed to open the database connection.&quot;
}
CCuHdrSet hdrSet(&m_Database);
// This does not work
hdrSet.m_strFilter = &quot;[COMPATIBLE_UNIT] in ('S0440', S0460')&quot;;
// this does work
hdrSet.m_strFilter = &quot;[COMPATIBLE_UNIT]='S0440'&quot;;
// following statement doesnot work
/* if(!hdrSet.Open(AFX_DB_USE_DEFAULT_TYPE, &quot;SELECT [TITLE] FROM [tidcuhdr]&quot || hdrSet.IsEOF())
*/
// this statement does work but I only want certain records based on where clause
if(!hdrSet.Open() || hdrSet.IsEOF())
{
AfxMessageBox(&quot;Cannot find records.&quot;
}
while(!hdrSet.IsEOF()){
AfxMessageBox(hdrSet.m_TITLE);
hdrSet.MoveNext();
}
hdrSet.Close();
m_Database.Close();
}
catch(CDBException *e){
AfxMessageBox(e->m_strError);
}
}

Thanks for your continuing help and suggestions.

 

[fdsouth]

I used your code as a starting point which helped considerably. Now, I would like to pass values stored in CString objects to fields in the database that I've opened. How might I do that? Any help would be greatly appreciated.