ansitobstr.cpp

vc ADO 连接数据库

#import  <msado15.dll> rename("EOF", "adoEOF")

struct InitOle {
InitOle()  { ::CoInitialize(NULL); }
~InitOle() { ::CoUninitialize();   }
} _init_InitOle_;

BSTR AnsiToBSTR( LPTSTR m_pchData )
{
   // Helper function derived from source of CString::AllocSysString()
   BSTR bstr = NULL;
#if defined(_UNICODE) || defined(OLE2ANSI)
   bstr = ::SysAllocStringLen(m_pchData, wcslen( m_pchData ) );
#else
   int nLen = MultiByteToWideChar(CP_ACP, 0, m_pchData,
                                  strlen( m_pchData ), NULL, NULL);
   bstr = ::SysAllocStringLen(NULL, nLen);
   if (bstr == NULL)
      return NULL;
   MultiByteToWideChar(CP_ACP, 0, m_pchData, 
                       strlen( m_pchData ), bstr, nLen);
#endif

   return bstr;
}

void main( void )
{
    HRESULT                 hr  = S_OK;
    ADODB::_RecordsetPtr    Rs1 = NULL;
    VARIANT                 Source;
    VARIANT                 Connect;

    VariantInit( &Source  );
    VariantInit( &Connect );

    // Note this demonstrates the code listing both for AnsiToBstr()
    // as well as ways to create a BSTR
    Source.vt       = VT_BSTR;
    Source.bstrVal  = AnsiToBSTR( "SELECT * FROM Authors");

    Connect.vt      = VT_BSTR;
    Connect.bstrVal = ::SysAllocString( L"DSN=AdoDemo;UID=admin;PWD=;" );


    hr = Rs1.CreateInstance( __uuidof( ADODB::Recordset ) );
    Rs1->Open( Source, Connect, 
               ADODB::adOpenForwardOnly, 
               ADODB::adLockReadOnly, -1 );
    Rs1->Close();
    Rs1 = NULL;
    ::MessageBox( NULL, "Success!", "", MB_OK );
}