It is used to fill the report
Example code
CComPtr<ISmpReport>m_SmpReport;
HRESULT hr=SmpReport.CoCreateInstance(CLSID_SmpReport);
CString strSQLQuery=_T(""SELECT * FROM ""+ TableName);
bstrSQLQuery=strSQLQuery.AllocSysString();
m_SmpReport->FillReport(m_bstrSQLQuery);