This example uses the Delete method to remove a specified record from a Recordset.


  
  
  
  
// BeginDeleteCpp
#import "C:\Program Files\Common Files\System\ADO\msado15.dll"     no_namespace rename("EOF", "EndOfFile")

#include <stdio.h>
#include <ole2.h>
#include <conio.h>
#include "DeleteX.h"

//Function Declarations.
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void DeleteX(void);
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, '
')) // Exhaust the input buffer. do { fgets(strExBuff, sizeof(strExBuff), stdin); }while (!strrchr(strExBuff, '
')); else // Replace '
' with '\0' strDest[strrchr(strDest, '
') - strDest] = '\0'; return pstrRet; } /////////////////////////////////////////////////////////// // // // Main Function // // // /////////////////////////////////////////////////////////// void main() { if(FAILED(::CoInitialize(NULL))) return; DeleteX(); // Wait here for the user to see the output printf("

Press any key to continue..."); getch(); ::CoUninitialize(); } /////////////////////////////////////////////////////////// // // // DeleteX Function // // // /////////////////////////////////////////////////////////// void DeleteX(void) { // Define ADO object pointers. // Initialize pointers on define. // These are in the ADODB:: namespace. _RecordsetPtr pRstRoySched = NULL; // Define Other Variables IADORecordBinding *picRs = NULL; //Interface Pointer declared. CRoySchedRs royschrs; //C++ class object HRESULT hr = S_OK; char strTitleID[10], strTmpTitleID[10]=""; long longHiRange; int intRoyalty, intLoRange, cnt=0; bool blnFound = TRUE; _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" "Initial Catalog='pubs';Integrated Security='SSPI';"); try { // Open RoySched table TESTHR(pRstRoySched.CreateInstance(__uuidof(Recordset))); pRstRoySched->CursorLocation = adUseClient; pRstRoySched->CursorType = adOpenStatic; pRstRoySched->LockType = adLockBatchOptimistic; TESTHR(pRstRoySched->Open("SELECT * FROM roysched WHERE" " royalty = 20",strCnn,adOpenStatic,adLockBatchOptimistic, adCmdText)); // Prompt for a record to delete. printf("Before delete there are %d titles with 20 percent " "royalty :
", pRstRoySched->RecordCount); // Open an IADORecordBinding interface pointer which we'll use // for Binding Recordset to a class. TESTHR(pRstRoySched->QueryInterface( __uuidof(IADORecordBinding),(LPVOID*)&picRs)); // Bind the Recordset to a C++ Class here TESTHR(picRs->BindToRecordset(&royschrs)); while(!(pRstRoySched->EndOfFile)) { printf("%s
", royschrs.lemp_titleidStatus == adFldOK ? royschrs.m_sz_titleid : "<NULL>"); pRstRoySched->MoveNext(); } printf("
Enter the ID of a record to delete: "); mygets(strTitleID, 10); // Converting the title_id to upper case for( cnt=0; cnt<10; cnt++) { if(strTitleID[cnt] != NULL) { if( IsCharAlpha( strTitleID[cnt]) ) { if( islower( strTitleID[cnt]) ) strTmpTitleID[cnt] = _toupper(strTitleID[cnt]); else strTmpTitleID[cnt] = strTitleID[cnt]; } else { strTmpTitleID[cnt] = strTitleID[cnt]; } } } // Move to the record and save data so it can be restored. pRstRoySched->PutFilter ("title_id = '" + (_bstr_t)(LPCSTR)strTmpTitleID + "'"); if(pRstRoySched->RecordCount != 0) { intLoRange = royschrs.m_sz_lorange; longHiRange = royschrs.m_sz_hirange; intRoyalty = royschrs.m_sz_royalty; // Delete the record pRstRoySched->Delete(adAffectCurrent); pRstRoySched->UpdateBatch(adAffectCurrent); } else { blnFound = FALSE; printf("This Title ID not available"); } // Show the results. VARIANT varFilter; varFilter.vt = VT_I2; varFilter.iVal = adFilterNone; pRstRoySched->PutFilter (varFilter); pRstRoySched->Requery(-1); // Bind the Recordset to a C++ Class here. TESTHR(picRs->BindToRecordset(&royschrs)); printf("
After delete there are %d titles with 20 percent" " royalty: ", pRstRoySched->RecordCount); while(!(pRstRoySched->EndOfFile)) { printf("
%s", royschrs.lemp_titleidStatus == adFldOK ? royschrs.m_sz_titleid : "<NULL>"); pRstRoySched->MoveNext(); } // Restore the data because this is a demonstration. if(blnFound) { // Set the final character of the destination string to NULL. royschrs.m_sz_titleid[sizeof(royschrs.m_sz_titleid)-1] = '\0'; // The source string will get truncated if its length is // longer than the length of the destination string minus one. strncpy(royschrs.m_sz_titleid,strTmpTitleID,sizeof(royschrs.m_sz_titleid)-1); royschrs.m_sz_lorange = intLoRange; royschrs.m_sz_hirange = longHiRange; royschrs.m_sz_royalty = intRoyalty; TESTHR(picRs->AddNew(&royschrs)); pRstRoySched->UpdateBatch(adAffectCurrent); } } catch(_com_error &e) { // Notify the user of errors if any. // Pass a connection pointer accessed from the Recordset. _variant_t vtConnect = pRstRoySched->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. //Release the IADORecordset Interface here if (picRs) picRs->Release(); if (pRstRoySched) if (pRstRoySched->State == adStateOpen) pRstRoySched->Close(); } /////////////////////////////////////////////////////////// // // // 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("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
"); printf("\tCode = %08lx
", e.Error()); printf("\tCode meaning = %s
", e.ErrorMessage()); printf("\tSource = %s
", (LPCSTR) bstrSource); printf("\tDescription = %s
", (LPCSTR) bstrDescription); } // EndDeleteCpp

DeleteX.h

  
  
  
  

// BeginDeleteH
#include "icrsint.h"

// This Class extracts titleid, lorange, hirange and royalty
// from the "roysched" table.

class CRoySchedRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CRoySchedRs)

    //Column empid is the 1st field in the recordset   

    ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_sz_titleid, 
         sizeof(m_sz_titleid), lemp_titleidStatus, TRUE)

    ADO_VARIABLE_LENGTH_ENTRY2(2, adInteger, m_sz_lorange, 
         sizeof(m_sz_lorange), lemp_lorangeStatus, TRUE)

    ADO_VARIABLE_LENGTH_ENTRY2(3, adInteger, m_sz_hirange, 
         sizeof(m_sz_hirange), lemp_hirangeStatus, TRUE)

    ADO_VARIABLE_LENGTH_ENTRY2(4, adInteger, m_sz_royalty, 
         sizeof(m_sz_royalty), lemp_royaltyStatus, TRUE)

END_ADO_BINDING()

public:

    CHAR     m_sz_titleid[10];
    ULONG    lemp_titleidStatus;
    ULONG    m_sz_lorange;
    ULONG    lemp_lorangeStatus;
    ULONG    m_sz_hirange;
    ULONG    lemp_hirangeStatus;
    ULONG    m_sz_royalty;
    ULONG    lemp_royaltyStatus;
};
// EndDeleteH

http://technet.microsoft.com/zh-cn/library/bb148274

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