How can I tell if an ADODB::_RecordsetPtr has already been created?

Question

I am trying to write a class that uses ADO to retrieve SQL records. The intent is for the class to maintain one private recordset an other methods move forward, retrieve fields, etc. This is a basic example of my class:

class SqlADO {
  private:
    ADODB::_RecordsetPtr _recordset;
  public:
    void Open(); //open the connection
    void Execute(const char* sql);  // creates or replaces current recordset
    void Next(); //moves recordset cursor forward
    void Field(const char* fieldName); //retrieves field name from current record of the recordset
};


void SqlConnection::Execute(const char* sql) {
    if(_recordset == NULL) { /* is this ok? */
        HRESULT hr;
        hr = _recordset.CreateInstance(__uuidof(ADODB::Recordset));

        if(FAILED(hr)){
            throw _com_error(hr);
        }
    }

    if(_recordset->State != ADODB::adStateClosed) {
        _recordset->Close();
    }

    try{
    _recordset->Open(sql.c_str(),
        _connection.GetInterfacePtr(),
        ADODB::adOpenForwardOnly,
        ADODB::adLockReadOnly,
        ADODB::adCmdText);
    } catch(_com_error &e) {
        throw;
    }
}

My Questions:

• In the Execute method, how can I check to see that the recordset instance has been created (or do I need to) so that I can close it first?
• Do you know of any good ADO COM Interop references?