MDAC 2.5 SDK - ADO

AbsolutePage, PageCount, and PageSize Properties Example (VC++)

See Also

This example uses the AbsolutePage, PageCount, and PageSize properties to display names and hire dates from the Employee table, five records at a time.

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


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

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

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

    AbsolutePageX();
    
    ::CoUninitialize();
}


/////////////////////////////////////////////////////////////
//                                                         //
//      AbsolutePageX Function                             //
//                                                         //
/////////////////////////////////////////////////////////////

void AbsolutePageX(void)
{

    // 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 
    HRESULT hr = S_OK;  
    _bstr_t strMessage; 

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

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

    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 here 
        TESTHR(hr =   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));

        //Display Names and hire dates, five records at a time
        pRstEmployees->PageSize = 5;

        int intPageCount = pRstEmployees->PageCount;
        
        for(int intPage=1;intPage<=intPageCount;intPage++)
        {
            pRstEmployees->put_AbsolutePage((enum PositionEnum)intPage);
            strMessage = "";

            for(int intRecord=1;
                intRecord<=pRstEmployees->PageSize;intRecord++)
            {
                printf("\t%s %s %.10s\n", 
                    emprs.lau_fnameStatus == adFldOK ? 
                    emprs.m_szau_fname : "<NULL>",
                    emprs.lau_lnameStatus == adFldOK ? 
                    emprs.m_szau_lname : "<NULL>",
                    emprs.lau_hiredateStatus == adFldOK ? 
                    emprs.m_szau_hiredate : "<NULL>");

                pRstEmployees->MoveNext();

                if(pRstEmployees->EndOfFile)
                    break;
                }

            printf("\n Press any key to continue...");getch();

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

        // Clean up objects before exit.
        pRstEmployees->Close();

        //Release the IADORecordset Interface here
        if (picRs) 
            picRs->Release();
    }

    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;
        }
    }
}

///////////////////////////////////////////////////////////
//                                                       //
//      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;

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

AbsolutePageX.h:

#include "icrsint.h"

//This Class extracts only fname,lastname and hire_date  

class CEmployeeRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CEmployeeRs)

    //Column fname is the 2nd field in the table   
    ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szau_fname, 
        sizeof(m_szau_fname), lau_fnameStatus, FALSE)

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

    ADO_VARIABLE_LENGTH_ENTRY2(8, adVarChar, m_szau_hiredate, 
        sizeof(m_szau_hiredate), lau_hiredateStatus, TRUE)

END_ADO_BINDING()

public:
    CHAR   m_szau_lname[41];
    ULONG  lau_lnameStatus;
    CHAR   m_szau_fname[41];
    ULONG  lau_fnameStatus;
    CHAR   m_szau_hiredate[40];
    ULONG  lau_hiredateStatus;
};