Provider and DefaultDatabase Properties Example (VC++)

This example demonstrates the Provider property by opening three Connection objects using different providers. It also uses the DefaultDatabase property to set the default database for the Microsoft ODBC Provider.

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

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

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

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

    ProviderX();

    ::CoUninitialize();
}

/////////////////////////////////
//                             //
//    ProviderX Function       //
//                             //
/////////////////////////////////

void ProviderX(void) 
{
    HRESULT    hr = S_OK;

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _ConnectionPtr    pConnection1    = NULL;
    _ConnectionPtr    pConnection2     = NULL;
    _ConnectionPtr    pConnection3     = NULL;

    try
    {
        // Open a Connection using the Microsoft ODBC provider.
        TESTHR(pConnection1.CreateInstance(__uuidof(Connection)));
        pConnection1->ConnectionString = "driver={SQL Server};"
            "server='MySqlServer';user id='MyUserId';password='MyPassword';";
        pConnection1->Open("","","",adConnectUnspecified);
        pConnection1->DefaultDatabase = "pubs";

        // Display the provider
        printf("\n\nConnection1 provider: %s \n\n",
            (LPCSTR)pConnection1->Provider);

        // Open a connection using the OLE DB Provider for Microsoft Jet.
        TESTHR(pConnection2.CreateInstance(__uuidof(Connection)));
        pConnection2->Provider = "Microsoft.Jet.OLEDB.4.0";

        char *sConn = "c:\\Program Files\\Microsoft Office\\Office\\"
            "Samples\\Northwind.mdb";

        pConnection2->Open(sConn,"admin","",NULL);

        // Display the provider
        printf("Connection2 provider: %s \n\n",(LPCSTR)pConnection2->
            Provider);

        // Open a Connection using the Microsoft SQL Server provider.
        TESTHR(pConnection3.CreateInstance(__uuidof(Connection)));
        pConnection3->Provider = "sqloledb";
        pConnection3->Open("Data Source='MySqlServer';Initial Catalog='pubs';",
            "MyUserId","MyPassword",NULL);

        // Display the provider.
        printf("Connection3 provider: %s\n\n",(LPCSTR)pConnection3->
            Provider);
    }

    catch (_com_error &e)
    {
        // Notify the user of errors if any.
        PrintProviderError(pConnection1);
        if(pConnection2) PrintProviderError(pConnection2);
        if(pConnection3) PrintProviderError(pConnection3);
        PrintComError(e);
    }

    if (pConnection1)
        if (pConnection1->State == adStateOpen)
            pConnection1->Close();
    if (pConnection2)
        if (pConnection2->State == adStateOpen)
            pConnection2->Close();
    if (pConnection3)
        if (pConnection3->State == adStateOpen)
            pConnection3->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;

    if( (pConnection->Errors->Count) > 0)
    {
        long nCount = pConnection->Errors->Count;

        // Collection ranges from 0 to nCount -1.
        for(long 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("Error\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);
}
// EndProviderCpp

See Also

Connection Object | DefaultDatabase Property | Provider Property