DOC: ADO VC Tutorial in MSDN Has Compile/Run-Time Errors

• Microsoft Data Access SDK, versions 2.0, 2.1
• ActiveX Data Objects (ADO), versions 2.0, 2.1

SUMMARY

The ADO Visual C++ Tutorial in MSDN has problems in the code that can cause one or more compilation or run-time errors.

To get to this tutorial, do the following:

1. Start MSDN, click the Contents tab.



2. Navigate as follows: Platform SDK, Data Access Service, Microsoft Data Access 2.1 SDK, Microsoft ActiveX Data Objects (ADO), Microsoft ADO Programmer's Reference.



3. From the Microsoft ADO Programmer's Reference, navigate as follows: Learning ADO, ADO and RDS Tutorials, ADO Tutorial, ADO Tutorial (VC++).

Error Code = 800a0bb9 Code meaning = Unknown error 0x800A0BB9 Source = ADODB.Recordset Description = The application is using arguments that are of the wrong type, are out of acceptable range, or are in conflict with one another.

 pRs->Open("select * from authors", 
         _variant_t (pConn),
         adOpenDynamic, adLockOptimistic, adCmdText); 

Error Code = 800a0cc1 Code meaning = Unknown error 0x800A0CC1 Source = ADODB.Properties Description = ADO could not find the object in the collection corresponding to the name or ordinal reference requested by the application.

 pRs->Fields->GetItem("au_lname")->Properties->GetItem("Optimize")->Value = true;  

MORE INFORMATION

Following is the code that corrects the above mentioned errors. Just replace the code from the sample with the following code:

// START ADO VC++ TUTORIAL
#define INITGUID
#import "c:\Program Files\Common Files\System\ADO\msado15.dll"    no_namespace rename("EOF", "EndOfFile")
#include <stdio.h>
#include <icrsint.h>

void dump_com_error(_com_error &e)
   {
   printf("Error\n");
   printf("\a\tCode = %08lx\n", e.Error());
   printf("\a\tCode meaning = %s", e.ErrorMessage());
   _bstr_t bstrSource(e.Source());
   _bstr_t bstrDescription(e.Description());
   printf("\a\tSource = %s\n", (LPCSTR) bstrSource);
   printf("\a\tDescription = %s\n", (LPCSTR) bstrDescription);
   }

class CCustomRs : 
   public CADORecordBinding
{
BEGIN_ADO_BINDING(CCustomRs)
   ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_szau_lname, 
         sizeof(m_szau_lname), lau_lnameStatus, false)
   ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szau_fname, 
         sizeof(m_szau_fname), lau_fnameStatus, false)
   ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_szphone,    
         sizeof(m_szphone),    lphoneStatus,    true)
END_ADO_BINDING()

public:
   CHAR   m_szau_lname[41];
   ULONG   lau_lnameStatus;
   CHAR   m_szau_fname[41];
   ULONG   lau_fnameStatus;
   CHAR   m_szphone[12];
   ULONG   lphoneStatus;
};

VOID   main()
   {
   HRESULT            hr;
   IADORecordBinding   *picRs = NULL;
   
   ::CoInitialize(NULL);

   try 
      {
      _ConnectionPtr pConn(__uuidof(Connection)); // FIX #1: DON'T USE PROGID!
      _RecordsetPtr pRs(__uuidof(Recordset));	  // FIX #2: DON'T USE PROGID!
      CCustomRs rs;

// Step 1: Open a connection

      pConn->Open("dsn=pubs;", "sa", "", adConnectUnspecified);

// Step 2: Create a command
// Step 3: Execute the command
		
	  pRs->CursorLocation = adUseClient; // FIX #3: NEED CLIENT CURSOR FOR BATCH UPDATES!
      pRs->Open("select * from authors",
         _variant_t((IDispatch*)pConn), // FIX #4:  MUST CAST SMART POINTER TO LPDISPATCH!
         adOpenDynamic, 
		 adLockBatchOptimistic,			 // FIX #5: MUST USE adLockBatchOptimistic
		 adCmdText);
      
      if (FAILED(hr = pRs->QueryInterface(__uuidof(IADORecordBinding), 
            (LPVOID*)&picRs)))
         _com_issue_error(hr);
      
      if (FAILED(hr = picRs->BindToRecordset(&rs)))
         _com_issue_error(hr);

// Step 4: Manipulate the data

      pRs->Fields->Item["au_lname"]->Properties->Item["Optimize"]->Value = true;  // FIX #6: USE PROPER SMART POINTER SYNTAX.
      //pRs->Fields->GetItem("au_lname")->Properties->GetItem("Optimize")->Value = true; 
      pRs->Sort = "au_lname ASC";
      pRs->Filter = "phone LIKE '415 5*'";

      pRs->MoveFirst();
      while (VARIANT_FALSE == pRs->EndOfFile)
         {
         printf("\a\tName: %s\t %s\tPhone: %s\n",  
            (rs.lau_fnameStatus == adFldOK ? rs.m_szau_fname : ""), 
            (rs.lau_lnameStatus == adFldOK ? rs.m_szau_lname : ""),
            (rs.lphoneStatus == adFldOK ? rs.m_szphone   : ""));

         if (rs.lphoneStatus == adFldOK)
            memcpy(rs.m_szphone, "777", 3);
            
         if (FAILED(hr = picRs->Update(&rs)))
            _com_issue_error(hr);

      // Change the current row of the Recordset. 
      // Recordset data for the new current row will automatically be 
      // extracted and placed in the CCustomRs C++ instance variables.
   
         pRs->MoveNext();
         }
      pRs->Filter = (long) adFilterNone;

// Step 5: Update the data

      pConn->BeginTrans();
      try 
         {
         pRs->UpdateBatch(adAffectAll);

         // Step 6, part A: Conclude the update 
         pConn->CommitTrans();
         }

      catch (_com_error)
         {
         // Step 6, part B: Conclude the update 
         pRs->Filter = (long) adFilterConflictingRecords;
         pRs->MoveFirst();
         while (VARIANT_FALSE == pRs->EndOfFile)
            {
            printf("\a\tConflict: Name = %s\t %s\n", 
               (rs.lau_fnameStatus == adFldOK ? rs.m_szau_fname : ""), 
               (rs.lau_lnameStatus == adFldOK ? rs.m_szau_lname : ""));
            pRs->MoveNext();
            }
         pConn->RollbackTrans();
         }
      }

   catch (_com_error &e)
      {
      dump_com_error(e);
      }

   CoUninitialize();
   }
// END ADO VC++ TUTORIAL 

REFERENCES

For additional information about using ADO in Visual C++, please see the following articles in the Microsoft Knowledge Base:

Q174565 FILE: Adovc.exe Demonstrates How to Use ADO with Visual C++

Q185033 FILE: Adoacc.exe Demonstrates Using ADO with Access 97

Additional query words: problem problematic MDAC

Keywords          : kbdocfix kbdocerr kbADO200 kbADO210 kbDatabase kbGrpVCDB kbGrpMDAC 
Version           : WINDOWS:2.0,2.1
Platform          : WINDOWS 
Issue type        : 

Last Reviewed: May 20, 1999