Parameters Collection, Command Property Example (VC++)

The following code demonstrates how to use the Command property with the Command object to retrieve parameter information for the procedure.

// This sample runs correctly only if procedure 'CustomerById'
// exists. If the procedure doesn't exist, please use 
// 'ADOXProceduresAppend.cpp' to creat it.

// BeginProcedureParametersCpp
#import "c:\Program Files\Common Files\system\ado\msadox.dll"     no_namespace
#import "c:\Program Files\Common Files\system\ado\msado15.dll"

#include "iostream.h"
#include "stdio.h"
#include "conio.h"

//Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void ProcedureParametersX(void);

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

    ProcedureParametersX();

    ::CoUninitialize();
}

//////////////////////////////////////////////////////////
//                                                      //
//      ProcedureParametersX Function                   //
//                                                      //
//////////////////////////////////////////////////////////
void ProcedureParametersX()
{
    HRESULT hr = S_OK;

    // Define ADOX object pointers.
    // Initialize pointers on define.
    // These are in the ADOX::  namespace.
    _CatalogPtr m_pCatalog = NULL;

    //Define ADODB object pointers.
    ADODB::_ConnectionPtr m_pCnn = NULL;
    ADODB::_CommandPtr m_pCommand = NULL;
    ADODB::_ParameterPtr m_pParameter = NULL;

    try 
    {
        TESTHR(hr = m_pCnn.CreateInstance(__uuidof(ADODB::Connection)));

        //Open the Connection
        m_pCnn->Open("Provider='Microsoft.JET.OLEDB.4.0';"
                "Data Source='c:\\Program Files\\Microsoft Office\\"
                "Office\\Samples\\Northwind.mdb';","","",NULL);

        TESTHR(hr = m_pCatalog.CreateInstance(__uuidof(Catalog)));

        //Open the catalog
        m_pCatalog->PutActiveConnection(_variant_t((IDispatch *)m_pCnn));

        //Get the command object
        m_pCommand = m_pCatalog->Procedures->GetItem("CustomerById")->
            GetCommand();

        _variant_t vIndex;

        //Retrieve Parameter information
        m_pCommand->Parameters->Refresh();
        for (long lIndex = 0; lIndex < m_pCommand->Parameters->Count;
            lIndex ++)
        {
            vIndex = lIndex;
            m_pParameter = m_pCommand->Parameters->GetItem(vIndex);
            cout << m_pParameter->Name << ":" << m_pParameter->Type << 
                "\n" << endl;
        }
    }
    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        _bstr_t bstrSource(e.Source());
        _bstr_t bstrDescription(e.Description());
          
        printf("\n\tSource :  %s \n\tdescription : %s \n ",
             (LPCSTR)bstrSource,(LPCSTR)bstrDescription);
    }

    catch(...)
    {
        cout << "Error occured in ProcedureParametersX...."<< endl;
    }
}
// EndProcedureParametersCpp