theneedforemptybstrandvariants.cpp

vc ADO 连接数据库

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

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

void main( void )
{
    _variant_t  vtEmpty (DISP_E_PARAMNOTFOUND, VT_ERROR);
    _variant_t  vtEmpty2(DISP_E_PARAMNOTFOUND, VT_ERROR);
    _bstr_t     bstrEmpty(L"");
    _bstr_t     Source(L"SELECT * FROM Authors");

    ADODB::_ConnectionPtr  Conn1 = NULL;
    ADODB::_RecordsetPtr   Rs1   = NULL;
    HRESULT                hr    = Conn1.CreateInstance( __uuidof( ADODB::Connection ) );

    Conn1->ConnectionString = "DSN=AdoDemo;UID=admin;PWD=;";
    Conn1->Open( bstrEmpty, bstrEmpty, bstrEmpty, -1 );
    Rs1 = Conn1->Execute( 
        Source, 
        &vtEmpty, 
        ADODB::adCmdText );

    Rs1->Close();
    Conn1->Close();

    ::MessageBox( NULL, "Success!", "", MB_OK );
}