It is used to fill the report
Example code
CComPtr<IReports>m_Reports;
HRESULT hr=m_Reports.CoCreateInstance(CLSID_Reports);
VARIANT varSQLQuery;
CString strSQLQuery = _T(""SELECT * FROM ""+ strTableName); //strTableName Should be a valid table name
varSQLQuery.vt=VT_BSTR;
varSQLQuery.bstrVal=strSQLQuery.AllocSysString();
m_Reports->FillReport(varSQLQuery);