AbsolutePosition and CursorLocation Properties Example (VC++)

This example demonstrates how the AbsolutePosition property can track the progress of a loop that enumerates all the records of a Recordset. It uses the CursorLocation property to enable the AbsolutePosition property by setting the cursor to a client cursor.

// BeginAbsolutePositionCpp
#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 "AbsolutePositionX.h"

//Function Declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void AbsolutePositionX(void);
void AbsolutePosition2X(void);
void PrintProviderError(_ConnectionPtr pConnection);

///////////////////////////////////////////////////////////
//                                                       //
//      Main Function                                    //
//                                                       //
///////////////////////////////////////////////////////////
void main()
{
    if(FAILED(::CoInitialize(NULL)))
        return;

    AbsolutePositionX();


    //Clear the screen for the next display   
    printf("Press any key to continue...");
    getch();
    system("cls"); 

    AbsolutePosition2X();

    ::CoUninitialize();
}

///////////////////////////////////////////////////////////
//                                                       //
//      AbsolutePositionX Function                       //
//                                                       //
///////////////////////////////////////////////////////////

void AbsolutePositionX(void)
{
    HRESULT hr = S_OK;  

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr  pRstEmployees  = NULL;

    //Define Other Variables
    //Interface Pointer declared.(VC++ Extensions)
    IADORecordBinding *picRs = NULL;
    CEmployeeRs emprs;                  //C++ class object
    _bstr_t strMessage;
    char chKey;

    //Open a recordset using a Client Cursor
    //For the Employee Table

    _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';"
        "Initial Catalog='pubs';Integrated Security='SSPI';");

    try
    {
        //Open a recordset.
        TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));

        //Use client cursor to enable Absoluteposition property.
        pRstEmployees->CursorLocation = adUseClient;

        //You have to explicitly pass the default Cursor type 
        //and LockType to the Recordset.
        TESTHR(  pRstEmployees->Open("employee", 
        strCnn,adOpenForwardOnly,adLockReadOnly,adCmdTable));

        // Open an IADORecordBinding interface pointer which we'll use 
        // for Binding Recordset to a class.
        TESTHR(pRstEmployees->QueryInterface(
            __uuidof(IADORecordBinding),(LPVOID*)&picRs));

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

        strMessage= "";

        //Enumerate recordset
        do
        {
            //Display Current Record Information
            printf("Employee : %s \n record %ld of %d", 
                emprs.lau_lnameStatus == adFldOK ? 
                emprs.m_szau_lname : "<NULL>",
                pRstEmployees->AbsolutePosition, 
                    pRstEmployees->RecordCount);

            printf("\nContinue?(y/n)  :");

            do
            {
                chKey = getch();
            }while(chKey != 'y' && chKey !='n');

            //Clear the Screen for the next output   
            system("cls");

            if(chKey == 'n')
                break;

            strMessage = "";   
            pRstEmployees->MoveNext();   
        }while(!(pRstEmployees->EndOfFile));
    }
    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        _variant_t vtConnect = pRstEmployees->GetActiveConnection();

        // GetActiveConnection returns connect string if connection
        // is not open, else returns Connection object.
        switch(vtConnect.vt)
        {
            case VT_BSTR:
                printf("Error:\n");
                printf("Code = %08lx\n", e.Error());
                printf("Message = %s\n", e.ErrorMessage());
                printf("Source = %s\n", (LPCSTR) e.Source());
                printf("Description = %s\n", (LPCSTR) e.Description());
                break;
            case VT_DISPATCH:
                PrintProviderError(vtConnect);
                break;
            default:
                printf("Errors occured.");
                break;
        }
    }

    // Clean up objects before exit.
    //Release the IADORecordset Interface here   
    if (picRs)
        picRs->Release();
        
    if (pRstEmployees)
        if (pRstEmployees->State == adStateOpen)
            pRstEmployees->Close();
}


///////////////////////////////////////////////////////////
//                                                       //
//      AbsolutePosition2X Function                       //
//                                                       //
///////////////////////////////////////////////////////////

void AbsolutePosition2X(void)
{
    HRESULT hr = S_OK;  

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr  pRstEmployees  = NULL;

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

    //Open a recordset using a Client Cursor
    //For the Employee Table

    _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';"
        "Initial Catalog='pubs';Integrated Security='SSPI';");

    try
    {
        //Open a recordset.
        TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));

        //Use client cursor to enable Absoluteposition property.
        pRstEmployees->CursorLocation = adUseClient;

        //You have to explicitly pass the default Cursor type 
        //and LockType to the Recordset.
        TESTHR(pRstEmployees->Open("employee", 
          strCnn,adOpenStatic,adLockReadOnly,adCmdTable));

        // Open an IADORecordBinding interface pointer which we'll use 
        // for Binding Recordset to a class.
        TESTHR(pRstEmployees->QueryInterface(
            __uuidof(IADORecordBinding),(LPVOID*)&picRs));

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

        long lGoToPos = 21;

        pRstEmployees->AbsolutePosition = (PositionEnum)lGoToPos;

        //Display Current Record Information
        printf("Employee : %s \n record %ld of %d", 
            emprs.lau_lnameStatus == adFldOK ? emprs.m_szau_lname : "<NULL>", pRstEmployees->AbsolutePosition, 
            pRstEmployees->RecordCount);

        printf("\nPress any key to continue:");
        getch();
    }
    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        _variant_t vtConnect = pRstEmployees->GetActiveConnection();

        // GetActiveConnection returns connect string if connection
        // is not open, else returns Connection object.
        switch(vtConnect.vt)
        {
            case VT_BSTR:
                printf("Error:\n");
                printf("Code = %08lx\n", e.Error());
                printf("Message = %s\n", e.ErrorMessage());
                printf("Source = %s\n", (LPCSTR) e.Source());
                printf("Description = %s\n", (LPCSTR) e.Description());
                break;
            case VT_DISPATCH:
                PrintProviderError(vtConnect);
                break;
            default:
                printf("Errors occured.");
                break;
        }
    }

    // Clean up objects before exit.
    //Release the IADORecordset Interface here   
    if (picRs)
        picRs->Release();
        
    if (pRstEmployees)
        if (pRstEmployees->State == adStateOpen)
            pRstEmployees->Close();
}



///////////////////////////////////////////////////////////
//                                                       //
//      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("\t Error number: %x\t%s", 
                pErr->Number,(LPCSTR) pErr->Description);
        }
    }
}

// EndAbsolutePositionCpp

AbsolutePositionX.h

// BeginAbsolutePositionH
#include <ole2.h>
#include <stdio.h>
#include "icrsint.h"


//This Class extracts lastname.  

class CEmployeeRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CEmployeeRs)
    
    //Column lname is the 4th field in the recordset   

   ADO_VARIABLE_LENGTH_ENTRY2(4, adVarChar, m_szau_lname, 
         sizeof(m_szau_lname), lau_lnameStatus, TRUE)
   
END_ADO_BINDING()

public:
   CHAR   m_szau_lname[41];
   ULONG  lau_lnameStatus;

};
// EndAbsolutePositionH

See Also

AbsolutePosition Property | CursorLocation Property | Recordset Object