m_cmdStr=L"select * from t1";
try{m_pSet=m_pAdo->Execute(_bstr_t(m_cmdStr),&vtVal,adCmdText);}
catch(_com_error e)
{
MessageBox(L" 错误");
}
try{m_pSet->GetRows(adGetRowsRest,adBookmarkFirst,_variant_t(L"a"));}
catch(_com_error e)
{
_bstr_t bstr=e.Description();
CString str((LPCSTR)bstr);
MessageBox(str);提示：应用程序在当前操作中使用了错误类型的值
}
------解决方案--------------------------------------------------------
- C/C++ code
// testgetrows.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"// BeginGetRowsCpp#import "C:\Program Files\Common Files\System\ado\msado15.dll" \ no_namespace rename("EOF", "EndOfFile")#include <stdio.h>#include <ole2.h>#include <conio.h>// Function Declarationsinline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};void GetRowsX(void);bool GetRowsOK(_RecordsetPtr pRstTemp,int intNumber, _variant_t& avarData);void PrintProviderError(_ConnectionPtr pConnection);void PrintComError(_com_error &e);void main(){ if(FAILED(::CoInitialize(NULL))) return; GetRowsX(); ::CoUninitialize();}///////////////////////////////////////////////////////////// //// GetRowsX Function //// /////////////////////////////////////////////////////////////void GetRowsX(void){ HRESULT hr = S_OK; // Define string variables. _bstr_t strCnn("Provider='sqloledb';Data Source='127.0.0.1';" "Initial Catalog='pubs';Integrated Security='SSPI';"); // Define ADO object pointers. // Initialize pointers on define. // These are in the ADODB:: namespace. _RecordsetPtr pRstEmployees = NULL; try { // Open recordset with names and hire dates from employee table. TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset))); pRstEmployees->Open("SELECT fName, lName, hire_date " "FROM Employee ORDER BY lName",strCnn, adOpenStatic, adLockReadOnly,adCmdText); while (true) //continuous loop { int intLines = 0; // Get user input for number of rows. printf("\nEnter number of rows to retrieve (0 to exit): "); int intRows; scanf("%d", &intRows); if (intRows <= 0) break; //Clear the screen for the next display system("cls"); // If GetRowsOK is successful, print the results, // noting if the end of the file was reached. _variant_t avarRecords; if (GetRowsOK(pRstEmployees, intRows, avarRecords)) { long lUbound; HRESULT hr = SafeArrayGetUBound(avarRecords.parray, 2,&lUbound); if (hr == 0) { if (intRows > lUbound + 1) { printf("\n(Not enough records in Recordset to " "retrieve %d rows)\n", intRows); } } printf("%d records found.", lUbound+1); // Print the retrieved data. for (int intRecords = 0;intRecords < lUbound+1; intRecords++) { printf("\n "); long rgIndices[2]; rgIndices[0] = 0; rgIndices[1] = intRecords; _variant_t result; result.vt = VT_BSTR; hr= SafeArrayGetElement(avarRecords.parray, rgIndices, &result); if (hr == 0){printf("%s ",(LPCSTR)(_bstr_t)result);} rgIndices[0] = 1; hr= SafeArrayGetElement(avarRecords.parray, rgIndices, &result); if (hr == 0){printf("%s, ",(LPCSTR)(_bstr_t)result);} rgIndices[0] = 2; hr= SafeArrayGetElement(avarRecords.parray, rgIndices, &result); if (hr == 0){printf("%s",(LPCSTR)(_bstr_t)result);} intLines ++; if (intLines % 10 == 0) { printf("\nPress any key to continue..."); getch(); intLines = 0; //Clear the screen for the next display system("cls"); } } } else { // Assuming the GetRows error was due to data // changes by another user, use Requery to // refresh the Recordset and start over. printf("GetRows failed--retry?\n"); char chKey; do { chKey = getch(); }while(toupper(chKey) != 'Y' && toupper(chKey) != 'N'); if(toupper(chKey) == 'Y') { pRstEmployees->Requery(adOptionUnspecified); } else { printf("GetRows failed!\n"); break; } } // Because using GetRows leaves the current // record pointer at the last record accessed, // move the pointer back to the beginning of the // Recordset before looping back for another search. pRstEmployees->MoveFirst(); } } catch(_com_error &e) { // Notify the user of errors if any. // Pass a connection pointer accessed from the Recordset. _variant_t vtConnect = pRstEmployees->GetActiveConnection(); // GetActiveConnection returns connect string if connection // is not open, else returns Connection object. switch(vtConnect.vt) { case VT_BSTR: PrintComError(e); break; case VT_DISPATCH: PrintProviderError(vtConnect); break; default: printf("Errors occured."); break; } } //Clean up objects before exit. if (pRstEmployees) if (pRstEmployees->State == adStateOpen) pRstEmployees->Close();}bool GetRowsOK(_RecordsetPtr pRstTemp,int intNumber, _variant_t& avarData){ // Store results of GetRows method in array. avarData = pRstTemp->GetRows(intNumber); // Return False only if fewer than the desired // number of rows were returned, but not because the // end of the Recordset was reached. long lUbound; HRESULT hr = SafeArrayGetUBound(avarData.parray,2,&lUbound); if (hr == 0) { if ((intNumber > lUbound + 1) && (!(pRstTemp->EndOfFile))) return false; else return true; } else { printf ("\nUnable to Get the Array's Upper Bound\n"); return false; }}///////////////////////////////////////////////////////////// //// PrintProviderError Function //// /////////////////////////////////////////////////////////////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, (LPCSTR) pErr->Description); } }}///////////////////////////////////////////////////////////// //// PrintComError Function //// /////////////////////////////////////////////////////////////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);}// EndGetRowsCpp