Type-Eigenschaft (Beispiel) (VC++)

Gilt für: Access 2013, Office 2013

Dieses Beispiel veranschaulicht die Type-Eigenschaft. Dabei handelt es sich um ein Modell eines Hilfsprogramms, mit dem die Namen und Typen einer Auflistung aufgeführt werden, wie z. B. Properties, Fields usw.

Wir müssen das Recordset nicht öffnen, um auf seine Properties-Auflistung zuzugreifen. sie entstehen, wenn das Recordset-Objekt instanziiert wird. Wenn Sie die CursorLocation-Eigenschaft jedoch auf adUseClient festlegen, werden der Properties-Auflistung des Recordset-Objekts mehrere dynamische Eigenschaften hinzugefügt, was das Beispiel etwas interessanter macht. Zur Veranschaulichung verwenden wir explizit die Item-Eigenschaft , um auf jedes Property-Objekt zuzugreifen.

 
// BeginTypePropertyCpp 
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" no_namespace rename("EOF", "EndOfFile") 
 
#include <ole2.h> 
#include <stdio.h> 
#include<conio.h> 
 
// Function declarations 
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);}; 
void TypeX(); 
void PrintComError(_com_error &e); 
 
////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 TypeX(); 
 
 ::CoUninitialize(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// TypeX Function // 
// // 
////////////////////////////////////////////////////////// 
void TypeX() 
{ 
 HRESULT hr = S_OK; 
 
 // Define ADO object pointers. 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace 
 _RecordsetPtr pRst = NULL; 
 PropertyPtr pProperty = NULL; 
 
 //Define Other Variables 
 _bstr_t strMsg; 
 _variant_t vIndex; 
 int intLineCnt = 0; 
 
 try 
 { 
 TESTHR(pRst.CreateInstance (__uuidof(Recordset))); 
 
 // Set the Recordset Cursor Location 
 pRst->CursorLocation = adUseClient; 
 
 for (short iIndex = 0; iIndex <= (pRst->Properties-> 
 GetCount() - 1);iIndex++) 
 { 
 vIndex = iIndex; 
 pProperty = pRst->Properties->GetItem(vIndex); 
 
 int propType = (int)pProperty->GetType(); 
 switch(propType) 
 { 
 case adBigInt: 
 strMsg = "adBigInt"; 
 break; 
 case adBinary: 
 strMsg = "adBinary"; 
 break; 
 case adBoolean: 
 strMsg = "adBoolean"; 
 break; 
 case adBSTR: 
 strMsg = "adBSTR"; 
 break; 
 case adChapter: 
 strMsg = "adChapter"; 
 break; 
 case adChar: 
 strMsg = "adChar"; 
 break; 
 case adCurrency: 
 strMsg = "adCurrency"; 
 break; 
 case adDate: 
 strMsg = "adDate"; 
 break; 
 case adDBDate: 
 strMsg = "adDBDate"; 
 break; 
 case adDBTime: 
 strMsg = "adDBTime"; 
 break; 
 case adDBTimeStamp: 
 strMsg = "adDBTimeStamp"; 
 break; 
 case adDecimal: 
 strMsg = "adDecimal"; 
 break; 
 case adDouble: 
 strMsg = "adDouble"; 
 break; 
 case adEmpty: 
 strMsg = "adEmpty"; 
 break; 
 case adError: 
 strMsg = "adError"; 
 break; 
 case adFileTime: 
 strMsg = "adFileTime"; 
 break; 
 case adGUID: 
 strMsg = "adGUID"; 
 break; 
 case adIDispatch: 
 strMsg = "adIDispatch"; 
 break; 
 case adInteger: 
 strMsg = "adInteger"; 
 break; 
 case adIUnknown: 
 strMsg = "adIUnknown"; 
 break; 
 case adLongVarBinary: 
 strMsg = "adLongVarBinary"; 
 break; 
 case adLongVarChar: 
 strMsg = "adLongVarChar"; 
 break; 
 case adLongVarWChar: 
 strMsg = "adLongVarWChar"; 
 break; 
 case adNumeric: 
 strMsg = "adNumeric"; 
 break; 
 case adPropVariant: 
 strMsg = "adPropVariant"; 
 break; 
 case adSingle: 
 strMsg = "adSingle"; 
 break; 
 case adSmallInt: 
 strMsg = "adSmallInt"; 
 break; 
 case adTinyInt: 
 strMsg = "adTinyInt"; 
 break; 
 case adUnsignedBigInt: 
 strMsg = "adUnsignedBigInt"; 
 break; 
 case adUnsignedInt: 
 strMsg = "adUnsignedInt"; 
 break; 
 case adUnsignedSmallInt: 
 strMsg = "adUnsignedSmallInt"; 
 break; 
 case adUnsignedTinyInt: 
 strMsg = "adUnsignedTinyInt"; 
 break; 
 case adUserDefined: 
 strMsg = "adUserDefined"; 
 break; 
 case adVarBinary: 
 strMsg = "adVarBinary"; 
 break; 
 case adVarChar: 
 strMsg = "adVarChar"; 
 break; 
 case adVariant: 
 strMsg = "adVariant"; 
 break; 
 case adVarNumeric: 
 strMsg = "adVarNumeric"; 
 break; 
 case adVarWChar: 
 strMsg = "adVarWChar"; 
 break; 
 case adWChar: 
 strMsg = "adWChar"; 
 break; 
 default: 
 strMsg = "*UNKNOWN*"; 
 break; 
 } 
 
 intLineCnt++; 
 if (intLineCnt%20 == 0) 
 { 
 printf("\nPress any key to continue...\n"); 
 getch(); 
 } 
 printf ("Property %d : %s,Type = %s\n",iIndex, 
 (LPCSTR)pProperty->GetName(),(LPCSTR)strMsg); 
 } 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 PrintComError(e); 
 } 
} 
 
////////////////////////////////////////////////////////// 
// // 
// 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); 
} 
// EndTypePropertyCpp