PRB: Known OLE DB Provider Problems with Visual C++ 6.0 Wizards

• Microsoft Visual C++, 32-bit Editions, version 6.0

SUMMARY

MORE INFORMATION

1. Microsoft OLE DB Provider for ODBC Drivers / SQL Server 6.5 ODBC
   
   
   1. If the wizard is used with a stored procedure that does not have parameters, the wizard generates incorrect syntax.
      
      The following represents a sample stored procedure:

      
                CREATE PROCEDURE spMyProc
                AS
                return 5
            

      The wizard includes the following command in the generated code:

      
                { ? = call dbo.spMyProc;1() }
            

      When you open the rowset containing this command, you receive a DB_E_ERRORSINCOMMAND return value.
      
      To work around this issue, remove the parentheses and recompile the code. This is By Design in the ODBC specification.
   
   
   
   2. Generation of column map for stored procedure resultset not supported
      
      If you use a stored procedure that has a resultset with the wizard, a column map for the resultset is not generated. Note that a parameter is generated.
      
      You need to manually generate the column map. Or, create a temporary table with the same column names as the stored procedure resultset and use the table with the wizard in a temporary project to generate a correct column map.
   
   
   



2. Microsoft OLE DB Provider for ODBC Drivers / Oracle ODBC Driver
   
   
   1. When you try to access Oracle functions and stored procedures, a fault occurs. This is a provider-related problem. A signed char is returned for any NUMBER data type without precision and scale specified.
      
      To work around this problem, you should change the data type to a DB_NUMERIC, change the column entry to a COLUMN_ENTRY_PS macro, and specify the precision/scale variable.
   
   
   



3. Microsoft OLE DB Provider for ODBC Drivers / Access ODBC Driver
   
   
   1. The wizard doesn't handle long parameters for the Invoices Filter query properly (Northwind database). It doesn't emit anything for the OrderID parameter.
      
      To work around the problem add a COLUMN_ENTRY(1, m_lOrderID) to the parameter map (be sure to define a member variable of type Long for m_lOrderID).
   
   
   
   2. When you use the OLEDB for ODBC provider with the ATL Consumer Wizard or MFC AppWizard and you use a table that has more than one storage column, the emitted code tries to bind to each storage column. Due to the provider limitation the code fails; the call to IRowset::GetData() to retrieve the initial rowset returns E_NOINTERFACE. You either need to remove the extra column entry in the column map and the SELECT statement, or move the column into a separate accessor.
      
      For more information refer to the "OLE DB for ODBC Provider" section in the DASDK documentation in MSDN and MSDASQLreadme.txt.
   
   
   



4. Microsoft OLE DB Provider for ODBC Drivers / Text ODBC Driver
   
   
   1. Some text files do not appear to create any bindings for the accessor (i.e. the COLUMN_ENTRY map is empty). This causes an error when you open the rowset.
      
      The user not defining the format for the file causes the problem. To fix this problem, go to the ODBC Administrator, configure the ODBC DSN for the text datasource you are using, select the Options tab and click Define Format. Once you have defined the format, the wizard generates the appropriate accessor and the rowset opens properly.
   
   
   



5. Microsoft OLE DB Provider for SQL Server (SQL Server 6.5)
   
   
   1. You must run the Instcat.sql file (included with SQL Server 6.5) for the provider to run correctly.
   
   
   
   2. Generation of column map for stored procedure result set not supported
      
      If you use a stored procedure that has a result set with the wizard, a column map for the result set is not generated. Note that a parameter map is generated.
      
      You need to manually create the column map. Or, create a temporary table with the same column names as the stored procedure result set and use the table with the wizard in a temporary project to generate a correct column map.
   
   
   
   3. If you use the wizard with a stored procedure that does not have parameters, the wizard generates incorrect syntax.
      
      The following represents a sample stored procedure:

      
                CREATE PROCEDURE spMyProc
                AS
                return 5
             

      The wizard includes the following command in the generated code:

      
                { ? = call dbo.spMyProc;1() }
                

      When you open the rowset that contains this command, you receive a DB_E_ERRORSINCOMMAND return value.
      
      The work around this issue, remove the parentheses and recompile the code.
   
   
   



6. Microsoft OLE DB Provider for Oracle
   
   
   1. ROWID data types are not mapped properly. You see an empty line in the COLUMN_MAP and no data entry for a ROWID map. You must manually add these.
   
   
   



7. Microsoft OLE DB Provider for JET 3.51
   
   
   1. The wizard doesn't properly handle long parameters for the Invoices Filter query (Northwind DB). The wizard doesn't emit anything for that line.
      
      In this case, the wizard does emit a return value but it is erroneous.
      
      To work around the problem, add a COLUMN_ENTRY(1, m_lOrderID) to the parameter map (be sure to define a member variable of type Long for m_lOrderID). Both of these should be in the accessor class.
      
      You also need to remove the return parameter type from the command text (i.e. remove the '? =' in the call Invoices Filter statement).
   
   
   
   2. The provider doesn't emit column information for queries (stored procedures) and views. If you attempt to generate a class using a view or query, you receive code that may not compile and won't run correctly.
      
      One workaround is to run Access directly, determine the correct data types and ordinals for the query/view, and then manually add them.
      
      Another workaround is to use the Microsoft OLE DB Provider for ODBC Drivers with the Access ODBC driver.
      
      These issues are known to happen with the versions of Microsoft OLE DB Providers that ship with Visual C++ 6.0.

      
                OLE DB for ODBC msdasql.dll  - 02.00.3002.11
                Jet             msjtor35.dll - 3.52.1527.4
                Oracle          msdaora.dll  - 02.00.3002.15
                SQL Server      sqloledb.dll - 07.00.0502
               

   
   
   

SYMPTOMS

Visual C++, version 6.0 includes support for OLE DB. Part of this support includes enhancing the MFC AppWizard and adding the new ATL Consumer Template Wizard. However, some problems that involve Microsoft OLE DB providers can occur. This article contains a list of these problems and suggested workarounds.

Keywords : kbDatabase kbJET kbOLEDB kbOracle kbProvider kbVC600
Version :
Platform : winnt
Issue type : kbprb