DeleteRule-Eigenschaft (VC++-Beispiel)

Gilt für: Access 2013, Office 2013

In diesem Beispiel wird die Verwendung der DeleteRule-Eigenschaft eines Key-Objekts veranschaulicht. Der Code fügt ein neues Table-Objekt an und definiert dann einen neuen Primärschlüssel, indem DeleteRule auf adRICascade festgelegt wird.

 
// BeginDeleteRuleCpp 
#import "c:\Program Files\Common Files\system\ado\msadox.dll" no_namespace 
#import "c:\Program Files\Common Files\system\ado\msado15.dll" 
 
#include "iostream.h" 
#include "stdio.h" 
#include "conio.h" 
 
//Function declarations 
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);}; 
void DeleteRuleX(void); 
 
////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 DeleteRuleX(); 
 
 ::CoUninitialize(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// DeleteRuleX Function // 
// // 
////////////////////////////////////////////////////////// 
void DeleteRuleX(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Define ADOX object pointers. 
 // Initialize pointers on define. 
 // These are in the ADOX:: namespace. 
 _KeyPtr m_pKeyPrimary = NULL; 
 _CatalogPtr m_pCatalog = NULL; 
 _TablePtr m_pTblNew = NULL; 
 
 // Define string variables. 
 _bstr_t strcnn("Provider='Microsoft.JET.OLEDB.4.0';" 
 "Data source = 'c:\\Program Files\\Microsoft Office" 
 "\\Office\\Samples\\Northwind.mdb';"); 
 try 
 { 
 TESTHR(hr = m_pKeyPrimary.CreateInstance(__uuidof(Key))); 
 TESTHR(hr = m_pCatalog.CreateInstance(__uuidof (Catalog))); 
 TESTHR(hr = m_pTblNew.CreateInstance(__uuidof(Table))); 
 
 // Connect the catalog. 
 m_pCatalog->PutActiveConnection(strcnn); 
 
 // Name new table. 
 m_pTblNew->Name = "NewTable"; 
 
 // Append a numeric and a text field to new table. 
 m_pTblNew->Columns->Append("NumField",adInteger,20); 
 m_pTblNew->Columns->Append("TextField",adVarWChar,20); 
 
 // Append the new table. 
 m_pCatalog->Tables->Append(_variant_t((IDispatch*)m_pTblNew)); 
 printf("Table 'NewTable' is added.\n"); 
 
 // Define the Primary key. 
 m_pKeyPrimary->Name = "NumField"; 
 m_pKeyPrimary->Type = adKeyPrimary; 
 m_pKeyPrimary->RelatedTable = "Customers"; 
 m_pKeyPrimary->Columns->Append("NumField",adInteger,20); 
 m_pKeyPrimary->Columns->GetItem("NumField")->RelatedColumn = 
 "CustomerId"; 
 m_pKeyPrimary->DeleteRule = adRICascade; 
 
 //to pass an optional column parameter to Key's Apppend method 
 _variant_t vOptional; 
 vOptional.vt = VT_ERROR; 
 vOptional.scode = DISP_E_PARAMNOTFOUND; 
 
 // Append the primary key. 
 m_pCatalog->Tables->GetItem("NewTable")->Keys->Append( 
 _variant_t((IDispatch*)m_pKeyPrimary), 
 adKeyPrimary,vOptional,L"",L""); 
 
 // Delete the table as this is a demonstration. 
 m_pCatalog->Tables->Delete(m_pTblNew->Name); 
 printf("Table 'NewTable' is deleted.\n"); 
 } 
 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 _bstr_t bstrSource(e.Source()); 
 _bstr_t bstrDescription(e.Description()); 
 
 printf("\n\tSource : %s \n\tdescription : %s \n ", 
 (LPCSTR)bstrSource,(LPCSTR)bstrDescription); 
 } 
 
 catch(...) 
 { 
 cout << "Error occured in include files...."<< endl; 
 } 
} 
// EndDeleteRuleCpp