PRB: DAO Error 3028 When Creating a DAO Workspace

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Edition, versions 4.0, 5.0
• The DAO SDK included with: - Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1, 4.2, 5.0

SYMPTOMS

The following DAO error 3028 may occur when you try to create a workspace DAO object:

   Can't start application. The system database is missing or opened
   exclusively by another user.

CAUSE

This error can occur if you have failed to specify a system database or have assigned the system database after performing operations with the database engine.

RESOLUTION

It is important that the SystemDB property of the database engine be set prior to performing any operations with the database engine. If you are using the dbDAO C++ classes included with the DAO SDK, you can set the system database by using code similar to this code:

   // get database engine object but don't fill its collections
   CdbDBEngine eng(FALSE, FALSE);

   // set the system database
   eng.SetSystemDB(_T("d:\\work\\sectest.mdw"));

   // Finish initializing the engine object
   eng.Start();

   CdbWorkspace wsp;

   // The following function call will generate the 3028
   // error if a System Database hasn't been assigned or if the
   // second argument of the constructor for CdbDBEngine didn't
   // receive FALSE.

   wsp= eng.CreateWorkspace(_T("Test"),_T("MyUserName"),
                            _T("MyPassword"));

If you are using the MFC DAO classes, use code similar to this code:

   //Initialize global MFC DAO engine
   AfxDaoInit( );
   DAODBEngine* pDBEngine = AfxDaoGetEngine( );

   // Set up system database
   COleVariant var( _T("d:\\work\\sectest.mdw"), VT_BSTRT );
   // NOTE: put_SystemDB was a late addition to DAO
   // and is not yet wrapped by MFC
   DAO_CHECK( pDBEngine->put_SystemDB( var.bstrVal ) );

   CDaoWorkspace wsp;
   wsp.Create(_T("Test"),_T("MyUserName"), _T("MyPassword"));

STATUS