IsolationLevel プロパティと Mode プロパティの使用例 (VC++)

適用先: Access 2013、Office 2013

この例では、Mode プロパティを使って排他的接続を開き、 IsolationLevel プロパティを使って他のトランザクションから独立したトランザクションを開きます。

 
// BeginIsolationLevelCpp 
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" no_namespace rename("EOF","EndOfFile") 
 
#include <ole2.h> 
#include <stdio.h> 
#include <conio.h> 
#include "IsolationLevelX.h" 
 
// Function Declarations 
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);}; 
void IsolationLevelX(void); 
void PrintProviderError(_ConnectionPtr pConnection); 
void PrintComError(_com_error &e); 
 
///////////////////////////////////////////////////////////////// 
// // 
// // 
// Main Function // 
// // 
// // 
///////////////////////////////////////////////////////////////// 
 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 IsolationLevelX(); 
 
 printf("Press any key to continue..."); 
 getch(); 
 ::CoUninitialize(); 
} 
 
///////////////////////////////////////////////////////////////// 
// // 
// IsolationLevelX() Function // 
// // 
///////////////////////////////////////////////////////////////// 
 
void IsolationLevelX(void) 
{ 
 // Define ADO ObjectPointers 
 // Initialize Pointers on define 
 // These are in the ADODB :: namespace 
 _RecordsetPtr pRstTitles = NULL; 
 _ConnectionPtr pConnection = NULL; 
 
 // Define other Variables 
 HRESULT hr = S_OK; 
 IADORecordBinding *picRs = NULL; // Interface Pointer Declared 
 CTitleRs titlers; // C++ Class Object 
 LPSTR p_TempStr = NULL; 
 
 //Assign Connection String to Variable 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "Initial Catalog='pubs';Integrated Security='SSPI';"); 
 
 try 
 { 
 // Open Connection and Titles Table 
 TESTHR(pConnection.CreateInstance(__uuidof(Connection))); 
 pConnection->Mode = adModeShareExclusive; 
 pConnection->IsolationLevel = adXactIsolated; 
 pConnection->Open(strCnn,"","",adConnectUnspecified); 
 
 TESTHR(pRstTitles.CreateInstance(__uuidof(Recordset))); 
 pRstTitles->CursorType = adOpenDynamic; 
 pRstTitles->LockType = adLockPessimistic; 
 
 pRstTitles->Open("titles",_variant_t((IDispatch*) pConnection, 
 true),adOpenDynamic,adLockPessimistic,adCmdTable); 
 
 pConnection->BeginTrans(); 
 
 // Display Connection Mode 
 if(pConnection->Mode == adModeShareExclusive) 
 { 
 printf("Connection Mode Is Exclusive"); 
 } 
 else 
 { 
 printf("Connection Mode Is Not Exclusive"); 
 } 
 
 // Display Isolation Level 
 if(pConnection->IsolationLevel == adXactIsolated) 
 { 
 printf("\n\nTransaction is Isolated"); 
 printf("\n\nPress any key to continue...\n\n"); 
 getch(); 
 } 
 else 
 { 
 printf("\n\nTransaction is not Isolated"); 
 printf("\n\nPress any key to continue...\n\n"); 
 getch(); 
 } 
 
 // Open an IADORecordBinding interface pointer which 
 // we will use for binding Recordset to a class 
 TESTHR(pRstTitles->QueryInterface( 
 __uuidof(IADORecordBinding),(LPVOID*)&picRs)); 
 
 // Bind the Recordset to a C++ class here 
 TESTHR(picRs->BindToRecordset(&titlers)); 
 
 // Change the type of psychology titles. 
 p_TempStr = (LPSTR) malloc(sizeof(titlers.m_szau_Type)); 
 
 while (!(pRstTitles->EndOfFile)) 
 { 
 // Set the final character of the destination string to NULL. 
 p_TempStr[sizeof(titlers.m_szau_Type)-1] = '\0'; 
 // The source string will get truncated if its length is 
 // longer than the length of the destination string minus one. 
 strncpy(p_TempStr,strtok(titlers.m_szau_Type," "),sizeof(titlers.m_szau_Type)-1); 
 
 // Compare type with psychology 
 if (!strcmp(p_TempStr,"psychology")) 
 { 
 // Set the final character of the destination string to NULL. 
 titlers.m_szau_Type[sizeof(titlers.m_szau_Type)-1] = '\0'; 
 // Copy "self_help" title field 
 // The source string will get truncated if its length is 
 // longer than the length of the destination string minus one. 
 strncpy(titlers.m_szau_Type,"self_help",sizeof(titlers.m_szau_Type)-1); 
 picRs->Update(&titlers); 
 } 
 pRstTitles->MoveNext(); 
 } 
 // Print current data in recordset. 
 pRstTitles->Requery(adOptionUnspecified); 
 
 // Open again IADORecordBinding interface pointer for Binding 
 // Recordset to a class. 
 TESTHR(pRstTitles->QueryInterface( 
 __uuidof(IADORecordBinding),(LPVOID*)&picRs)); 
 
 // ReBinding the Recordset to a C++ Class 
 TESTHR(picRs->BindToRecordset(&titlers)); 
 
 // Move to the first record of the title table 
 pRstTitles->MoveFirst(); 
 
 //Clear the screen for the next display 
 system("cls"); 
 
 while (!pRstTitles->EndOfFile) 
 { 
 printf("%s - %s\n",titlers.lau_TitleStatus == adFldOK ? 
 titlers.m_szau_Title :"<NULL>", 
 titlers.lau_TypeStatus == adFldOK ? 
 titlers.m_szau_Type :"<NULL>"); 
 pRstTitles->MoveNext(); 
 } 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 PrintProviderError(pConnection); 
 PrintComError(e); 
 } 
 
 // Clean up objects before exit. 
 //Release the IADORecordset Interface here 
 if (picRs) 
 picRs->Release(); 
 
 if (pRstTitles) 
 if (pRstTitles->State == adStateOpen) 
 pRstTitles->Close(); 
 if (pConnection) 
 if (pConnection->State == adStateOpen) 
 { 
 // Restore Original Data 
 pConnection->RollbackTrans(); 
 
 pConnection->Close(); 
 } 
 
 // Deallocate the memory 
 if (p_TempStr) 
 free(p_TempStr); 
} 
 
///////////////////////////////////////////////////////////////// 
// // 
// 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); 
} 
// EndIsolationLevelCpp 

IsolationLevelX.h

 
// BeginIsolationLevelH 
 
#include "icrsint.h" 
 
//This class extracts titles and type from Title table 
 
class CTitleRs : public CADORecordBinding 
{ 
BEGIN_ADO_BINDING(CTitleRs) 
 // Column title is the 2nd field in the table 
 ADO_VARIABLE_LENGTH_ENTRY2(2,adVarChar,m_szau_Title, 
 sizeof(m_szau_Title),lau_TitleStatus,FALSE) 
 // Column type is the 3rd field in the table 
 ADO_VARIABLE_LENGTH_ENTRY2(3,adVarChar,m_szau_Type, 
 sizeof(m_szau_Type),lau_TypeStatus,TRUE) 
END_ADO_BINDING() 
 
public: 
 CHAR m_szau_Title[81]; 
 ULONG lau_TitleStatus; 
 CHAR m_szau_Type[13]; 
 ULONG lau_TypeStatus; 
}; 
// EndIsolationLevelH