Append and CreateParameter Methods Example (VC++)

This example uses the Append and CreateParameter methods to execute a stored procedure with an input parameter.

// BeginAppendCpp
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \
    no_namespace rename("EOF", "EndOfFile")

#include <ole2.h>
#include <stdio.h>
#include "conio.h"
#include "AppendX.h"

//Function declaration
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void AppendX(VOID);
void PrintProviderError(_ConnectionPtr pConnection);

///////////////////////////////////////////////////////////
//                                                       //
//      Main Function                                    //
//                                                       //
///////////////////////////////////////////////////////////
void main()
{
   HRESULT  hr = S_OK;

   if(FAILED(::CoInitialize(NULL)))
      return;

   AppendX();
   
   //Wait here for the user to see the output.
   printf("\n\nPress any key to continue...");
   getch();
   ::CoUninitialize(); 
}


///////////////////////////////////////////////////////////
//                                                       //
//      AppendX Function                                 //
//                                                       //
///////////////////////////////////////////////////////////
VOID  AppendX(VOID)
{

     HRESULT hr = S_OK;

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr pRstByRoyalty = NULL;
    _RecordsetPtr pRstAuthors = NULL;  
    _CommandPtr   pcmdByRoyalty = NULL;
    _ParameterPtr pprmByRoyalty = NULL;
    _ConnectionPtr pConnection = NULL;
   

     //Define Other variables
     IADORecordBinding   *picRs = NULL;  //Interface Pointer declared.(VC++ Extensions)   
     CEmployeeRs emprs;          //C++ class object    

    _bstr_t strCnn("Provider=sqloledb;Data Source=MyServer;"
         "Initial Catalog=pubs;User Id=sa;Password=;");

    _bstr_t strMessage, strAuthorID;

     int intRoyalty;
     VARIANT vtRoyalty;

   try
   {
      //Open a Connection.
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
      hr = pConnection->Open(strCnn,"","",adConnectUnspecified);
      pConnection->CursorLocation = adUseClient;

      //Open Command Object with one Parameter
      TESTHR(pcmdByRoyalty.CreateInstance(__uuidof(Command)));
      pcmdByRoyalty->CommandText = "byroyalty";
      pcmdByRoyalty->CommandType = adCmdStoredProc;

      //Get parameter value and append parameter
      printf("Enter Royalty: ");
      scanf("%d",&intRoyalty);

      //Define Integer/variant.
      vtRoyalty.vt = VT_I2;
      vtRoyalty.iVal = intRoyalty;
      pprmByRoyalty = pcmdByRoyalty->CreateParameter("percentage",adInteger,adParamInput,sizeof(int),vtRoyalty);
      pcmdByRoyalty->Parameters->Append(pprmByRoyalty);
      
      pprmByRoyalty->Value  = vtRoyalty;
           
      //Create Recordset by executing the command
      pcmdByRoyalty->ActiveConnection = pConnection;
      pRstByRoyalty = pcmdByRoyalty->Execute(NULL,NULL,adCmdStoredProc); 

      //Open the authors table to get author names for display
      TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));

      //You have to explicitly pass the default Cursor type and LockType to the Recordset here
      hr = pRstAuthors->Open("authors",_variant_t((IDispatch*)pConnection,true),adOpenForwardOnly,adLockReadOnly,adCmdTable); 
    
      //Open an IADORecordBinding interface pointer which we'll use for Binding Recordset to a class    
      TESTHR(pRstAuthors->QueryInterface(__uuidof(IADORecordBinding),(LPVOID*)&picRs));

       //Bind the Recordset to a C++ Class here    
      TESTHR(picRs->BindToRecordset(&emprs));

      //Print current data in the recordset, adding
      //author names from author table.
      printf("Authors with %d percent royalty ",intRoyalty);

      while(!(pRstByRoyalty->EndOfFile))
      {
         strAuthorID = pRstByRoyalty->Fields->Item["au_id"]->Value;
         pRstAuthors->Filter = "au_id = '"+strAuthorID+"'";

         printf("\n"  "%s, %s  %s",emprs.lau_idStatus == adFldOK ? emprs.m_szau_id : "<NULL>",\
               emprs.lau_fnameStatus == adFldOK ? emprs.m_szau_fname : "<NULL>",\
               emprs.lau_lnameStatus == adFldOK ? emprs.m_szau_lname : "<NULL>");

         pRstByRoyalty->MoveNext(); 
         
      }

      //Release the IADORecordset Interface here   
      if (picRs)
      picRs->Release();
      
      pRstByRoyalty->Close();
      pRstAuthors->Close();
      pConnection->Close(); 
   }

   catch(_com_error &e)
   {
      _bstr_t bstrSource(e.Source());
      _bstr_t bstrDescription(e.Description());

      PrintProviderError(pConnection);

      printf("\n Source : %s \n Description : %s \n",(LPCSTR)bstrSource,(LPCSTR)bstrDescription);
   }

}


///////////////////////////////////////////////////////////
//                                                       //
//      PrintProviderError Function                      //
//                                                       //
///////////////////////////////////////////////////////////

VOID PrintProviderError(_ConnectionPtr pConnection)
{
   // Print Provider Errors from Connection object.
   // pErr is a record object in the Connection's Error collection.
   ErrorPtr    pErr  = NULL;
   long      nCount  = 0;    
   long      i     = 0;

   if( (pConnection->Errors->Count) > 0)
   {
      nCount = pConnection->Errors->Count;
      // Collection ranges from 0 to nCount -1.
      for(i = 0; i < nCount; i++)
      {
         pErr = pConnection->Errors->GetItem(i);
         printf("Error number: %x\n Error Description: %s\n", pErr->Number,(LPCSTR) pErr->Description);
      }
   }
}
// EndAppendCpp

AppendX.h:

// BeginAppendH 
#include "icrsint.h"


//This Class extracts only author id,fname,lastname    

class CEmployeeRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CEmployeeRs)
    
   //Column au_id is the 1st field in the recordset   

   ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_szau_id, 
         sizeof(m_szau_id), lau_idStatus, TRUE)

   ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szau_lname, 
         sizeof(m_szau_lname), lau_lnameStatus, TRUE)

   ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_szau_fname, 
         sizeof(m_szau_fname), lau_fnameStatus, TRUE)
   
END_ADO_BINDING()

public:

   CHAR m_szau_id[20];
   ULONG lau_idStatus;

   CHAR m_szau_fname[40];
   ULONG lau_fnameStatus;
   
   CHAR   m_szau_lname[40];
   ULONG  lau_lnameStatus;

};
// EndAppendH

Append and CreateParameter Methods Example (VC++)

See Also