FIX: Problems When Using an Oracle Data Source

WINDOWS        | WINDOWS NT

The information in this article applies to:

• The Microsoft Foundation Classes (MFC), included with: - Microsoft Visual C++ for Windows, versions 1.5, 1.51, and 1.52 - Microsoft Visual C++, 32-bit Edition, version(s) 2.2

SYMPTOMS

An application built to access an Oracle data source using the Microsoft Foundation Classes (MFC) may crash or throw a CDBException exception or generate oracle error ora-02019.

CAUSE

Two known Oracle-driver-specific problems are:

• AppWizard and ClassWizard generate an incorrect GetDefaultSQL() function for an Oracle data source table.
• A stack overflow may occur when connecting to an Oracle data source. (This behavior is specific to 16-bit applications.)

RESOLUTION

There is a bug in the wizards that causes them to generate an incorrect GetDefaultSQL() function when using an Oracle data source. Looking at the CRecordset's GetDefaultSQL() function you will see that an at sign ("@") has been placed between the table owner and the table name. For example, you may see:

   CString CMyRecordSet::GetDefaultSQL()
   {
       return "Dan@Customer";
   }

An application may also crash because of a stack overflow. The Oracle drivers use a large amount of stack space. If the stack overflows, it will write into the main data segment and cause undefined behavior after returning to the application. This may be resolved by increasing the stack size of your application.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Microsoft Visual C++, 32-bit Edition, version 4.0