--- title: "Refresh Method Example (VC++) | Microsoft Docs" ms.prod: sql ms.prod_service: connectivity ms.technology: connectivity ms.custom: "" ms.date: "01/19/2017" ms.reviewer: "" ms.topic: conceptual dev_langs: - "C++" helpviewer_keywords: - "Refresh method [ADO], VC++ example" ms.assetid: 3dc3443b-a1b0-4fbd-908a-6e274dec981c author: MightyPen ms.author: genemi --- # Refresh Method Example (VC++) This example demonstrates using the [Refresh](../../../ado/reference/ado-api/refresh-method-ado.md) method to refresh the [Parameters](../../../ado/reference/ado-api/parameters-collection-ado.md) collection for a stored procedure [Command](../../../ado/reference/ado-api/command-object-ado.md) object. ## Example ``` // BeginRefreshCpp.cpp // compile with: /EHsc /c #import "msado15.dll" no_namespace rename("EOF", "EndOfFile") #include #include #include #include "icrsint.h" // Class extracts lname,fname from authors table. class CAuthorsRs : public CADORecordBinding { BEGIN_ADO_BINDING(CAuthorsRs) // Column lname is the 2nd field in the recordset ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szau_lname, sizeof(m_szau_lname), lau_lnameStatus, TRUE) // Column fname is the 3rd field in the recordset. ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_szau_fname, sizeof(m_szau_fname), lau_fnameStatus, TRUE) END_ADO_BINDING() public: CHAR m_szau_fname[21]; ULONG lau_fnameStatus; CHAR m_szau_lname[41]; ULONG lau_lnameStatus; }; // Function declarations inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); }; void RefreshX(); void PrintProviderError(_ConnectionPtr pConnection); void PrintComError(_com_error &e); inline char* mygets(char* strDest, int n) { char strExBuff[10]; char* pstrRet = fgets(strDest, n, stdin); if (pstrRet == NULL) return NULL; if (!strrchr(strDest, '\n')) // Exhaust the input buffer. do { fgets(strExBuff, sizeof(strExBuff), stdin); } while (!strrchr(strExBuff, '\n')); else // Replace '\n' with '\0' strDest[strrchr(strDest, '\n') - strDest] = '\0'; return pstrRet; } int main() { if (FAILED(::CoInitialize(NULL))) return -1; RefreshX(); ::CoUninitialize(); } void RefreshX() { HRESULT hr = S_OK; // Define string variables. _bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';"); // Define ADO object pointers. Initialize pointers on define. These are in the ADODB:: namespace. _ConnectionPtr pConnection = NULL; _CommandPtr pCmdByRoyalty = NULL; _RecordsetPtr pRstByRoyalty = NULL; _RecordsetPtr pRstAuthors = NULL; IADORecordBinding *picRs = NULL; // Interface Pointer declared. CAuthorsRs authorsrs; // C++ class object char * token1; try { // Open connection. TESTHR(pConnection.CreateInstance(__uuidof(Connection))); pConnection->Open (strCnn, "", "", adConnectUnspecified); // Open a command object for a stored procedure, with one parameter. TESTHR(pCmdByRoyalty.CreateInstance(__uuidof(Command))); pCmdByRoyalty->ActiveConnection = pConnection; pCmdByRoyalty->CommandText = "byroyalty"; pCmdByRoyalty->CommandType = adCmdStoredProc; pCmdByRoyalty->Parameters->Refresh(); // Get parameter value and execute the command, storing the results in a recordset. char *strRoyalty; char strTemp[5]; do { printf("\n\nEnter royalty : "); mygets(strTemp, 5); strRoyalty = strtok_s(strTemp," \t", &token1); if (strRoyalty == NULL) { exit(1); } // if the input is not numeric then notify the user. if (!atoi(strRoyalty)) { printf("\nExpecting numeric value..."); continue; } } while (!atoi(strRoyalty)); _variant_t vtroyal; vtroyal.vt = VT_I2; vtroyal.iVal = atoi(strRoyalty); _variant_t Index; Index.vt = VT_I2; Index.iVal = 1; pCmdByRoyalty->GetParameters()->GetItem(Index)->PutValue(vtroyal); pRstByRoyalty = pCmdByRoyalty->Execute(NULL,NULL,adCmdStoredProc); // Open the Authors table to get author names for display. TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset))); pRstAuthors->Open ("authors", _variant_t((IDispatch *) pConnection, true), adOpenForwardOnly, adLockReadOnly, adCmdTable); // Open an IADORecordBinding interface pointer which we'll use for // Binding Recordset to a class. TESTHR(pRstAuthors->QueryInterface(__uuidof(IADORecordBinding),(LPVOID*)&picRs)); // Bind the Recordset to a C++ Class here. TESTHR(picRs->BindToRecordset(&authorsrs)); // Print current data in the recordset,adding // author names from Authors table. printf("Authors with %s percent royalty\n\n", strRoyalty); while (!(pRstByRoyalty->EndOfFile)) { _bstr_t strAuthorID = pRstByRoyalty->Fields->GetItem("au_id")->Value; printf(" %s",(LPCSTR) (_bstr_t) pRstByRoyalty->Fields->GetItem("au_id")->Value); pRstAuthors->Filter = "au_id ='"+strAuthorID+"'"; printf(", %s %s\n",authorsrs.lau_fnameStatus == adFldOK ? authorsrs.m_szau_fname : "", authorsrs.lau_lnameStatus == adFldOK ? authorsrs.m_szau_lname : ""); pRstByRoyalty->MoveNext(); } } catch (_com_error &e) { PrintProviderError(pConnection); PrintComError(e); } if (pRstByRoyalty) if (pRstByRoyalty->State == adStateOpen) pRstByRoyalty->Close(); if (pRstAuthors) if (pRstAuthors->State == adStateOpen) pRstAuthors->Close(); if (pConnection) if (pConnection->State == adStateOpen) pConnection->Close(); } void PrintProviderError(_ConnectionPtr pConnection) { // Print Provider Errors from Connection object. // pErr is a record object in the Connection's Error collection. ErrorPtr pErr = NULL; if ( (pConnection->Errors->Count) > 0) { long nCount = pConnection->Errors->Count; // Collection ranges from 0 to nCount -1. for (long i = 0 ; i < nCount ; i++) { pErr = pConnection->Errors->GetItem(i); printf("\t Error number: %x\t%s", pErr->Number, pErr->Description); } } } void PrintComError(_com_error &e) { _bstr_t bstrSource(e.Source()); _bstr_t bstrDescription(e.Description()); // Print COM errors. printf("Error\n"); printf("\tCode = %08lx\n", e.Error()); printf("\tCode meaning = %s\n", e.ErrorMessage()); printf("\tSource = %s\n", (LPCSTR) bstrSource); printf("\tDescription = %s\n", (LPCSTR) bstrDescription); } ``` ## Sample Input ``` 25 ``` ## Sample Output ``` Authors with 25 percent royalty 724-80-9391, Stearns MacFeathe 899-46-2035, Anne Ringer ``` ## See Also [Command Object (ADO)](../../../ado/reference/ado-api/command-object-ado.md) [Parameters Collection (ADO)](../../../ado/reference/ado-api/parameters-collection-ado.md) [Refresh Method (ADO)](../../../ado/reference/ado-api/refresh-method-ado.md)