MDAC 2.5 SDK - ADO

ActiveCommand Property Example (VC++)

See Also

This example demonstrates the ActiveCommand property.

A subroutine is given a Recordset object whose ActiveCommand property is used to display the command text and parameter that created the Recordset.

#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 "ActiveCommandX.h"

// Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void ActiveCommandX(void);
void ActiveCommandXprint(_RecordsetPtr   pRst);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

//////////////////////////////////////////////////////////
//                                                      //
//        Main Function                                 //
//                                                      //
//////////////////////////////////////////////////////////

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

    ActiveCommandX();

    ::CoUninitialize();
}

//////////////////////////////////////////////////////////
//                                                      //
//            ActiveCommandX Function                   //
//                                                      //
//////////////////////////////////////////////////////////

void ActiveCommandX(void) 
{
    HRESULT   hr = S_OK;

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

    //Definitions of other variables
    _bstr_t  strCnn("Provider=SQLOLEDB;Data Source=srv;”
                 “Initial Catalog=Pubs;User Id=sa;Password=;");
    _bstr_t  strName;
    CHAR strcharName[50];

    try
    {
        // Open connection.
        TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
        TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));
        TESTHR(pCmd.CreateInstance(__uuidof(Command)));

        printf("ActiveCommandX Example\n\n");
        printf("Enter an author's name (e.g., Ringer): ");
        gets(strcharName);
        char *tempStr = strtok(strcharName, " \t");
        strName = tempStr;

        pCmd->CommandText = "SELECT * FROM authors WHERE au_lname = ?";
        pCmd->Parameters->Append(pCmd->CreateParameter("LastName", 
            adChar, adParamInput, 20, strName));

        pConnection->Open (strCnn, "", "", NULL);

        pCmd->PutActiveConnection(_variant_t((IDispatch*)pConnection));

        pRstAuthors = pCmd->Execute(NULL,NULL,adCmdText);

        ActiveCommandXprint(pRstAuthors);

        // Clean up objects before exit.
        pRstAuthors->Close();
        pConnection->Close();
    }

    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        // Pass a connection pointer accessed from the Recordset.
        PrintProviderError(pConnection);
        PrintComError(e);
    }
}

//////////////////////////////////////////////////////////
//                                                      //
//              ActiveCommandXprint Function            //
//                                                      //
//////////////////////////////////////////////////////////

void ActiveCommandXprint(_RecordsetPtr   pRst = NULL)
{
    // Varible declaraion & initialization
    IADORecordBinding   *picRs  = NULL;  //Interface Pointer declared. 
    CAuthorsRs autrs;                    //C++ class object
    HRESULT hr;
    bstr_t strName;
    
    //Open an IADORecordBinding interface pointer which 
    //we'll use for Binding Recordset to a class.
    TESTHR(pRst->QueryInterface(
        __uuidof(IADORecordBinding),(LPVOID*)&picRs));

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

    strName = ((_CommandPtr)pRst->GetActiveCommand())->
                  GetParameters()->GetItem("LastName")->Value;

    printf("Command text = '%s'\n", 
        (LPCSTR)((_CommandPtr)pRst->GetActiveCommand())->CommandText);

    printf("Parameter = '%s'\n", (LPCSTR)strName);

    if (pRst->BOF)
        printf("Name = '%s'not found.", (LPCSTR)strName);
    else
    {
        printf ("Name = '%s  %s' author ID = '%s'",
          autrs.lau_fnameStatus == adFldOK ? autrs.m_au_fname : "<NULL>",
          autrs.lau_lnameStatus == adFldOK ? autrs.m_au_lname : "<NULL>",
          autrs.lau_idStatus == adFldOK ? autrs.m_au_id : "<NULL>");
    }

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

//////////////////////////////////////////////////////////
//                                                      //
//        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\t%s\n", 
                pErr->Number, (LPCSTR)pErr->Description);
        }
    }
}

//////////////////////////////////////////////////////////
//                                                      //
//       PrintComError Function                         //
//                                                      //
//////////////////////////////////////////////////////////

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

    // Print Com errors.  
    printf("\nError\n");
    printf("\tCode = %08lx\n", e.Error());
    printf("\tCode meaning = %s\n", e.ErrorMessage());
    printf("\tSource = %s\n", (LPCSTR) bstrSource);
    printf("\tDescription = %s\n", (LPCSTR) bstrDescription);
}

ActiveCommandX.h

#include "icrsint.h"

// This Class extracts id, fname, lname from authors table.

class CAuthorsRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CAuthorsRs)

    // Column au_id is the 1st field in the recordset   
    ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_au_id, 
         sizeof(m_au_id), lau_idStatus, TRUE)

    // Column au_fname is the 2nd field in the recordset   
    ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_au_fname, 
         sizeof(m_au_fname), lau_fnameStatus, TRUE)

    // Column au_lname is the 3rd field in the recordset   
    ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_au_lname, 
         sizeof(m_au_lname), lau_lnameStatus, TRUE)

END_ADO_BINDING()

public:

    char     m_au_id[21];
    ULONG    lau_idStatus;
    char     m_au_fname[41];
    ULONG    lau_fnameStatus;
    char     m_au_lname[41];
    ULONG    lau_lnameStatus;
};