Delete method example (VC++)

Applies to: Access 2013, Office 2013

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, '\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; 
} 
 
/////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
/////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 DeleteX(); 
 
 // Wait here for the user to see the output 
 printf("\n\nPress 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 :\n", 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\n", royschrs.lemp_titleidStatus == adFldOK ? 
 royschrs.m_sz_titleid : "<NULL>"); 
 pRstRoySched->MoveNext(); 
 } 
 
 printf("\nEnter 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("\nAfter delete there are %d titles with 20 percent" 
 " royalty: ", pRstRoySched->RecordCount); 
 
 while(!(pRstRoySched->EndOfFile)) 
 { 
 printf("\n%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\n", 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); 
} 
// 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