Attributes and Name Properties Example (VC++)

מאמר
11/18/2022
This example displays the value of the Attributes property for Connection, Field, and Property objects. It uses the Name property to display the name of each Field and Property object.
// BeginAttributesCpp.cpp  
// compile with: /EHsc  
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")  
  
#include <ole2.h>  
#include <stdio.h>  
#include <conio.h>  
#include "icrsint.h"  
  
// This class extracts LastName, FirstName, FaxPhone from Employees table  
  
class CEmployeeRs : public CADORecordBinding {  
   BEGIN_ADO_BINDING(CEmployeeRs)  
  
      // Column LastName is the 2nd field in the table  
      ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szemp_LastName, sizeof(m_szemp_LastName), lemp_LastNameStatus, TRUE)  
  
      // Column FirstName is the 17th field in the table  
      ADO_VARIABLE_LENGTH_ENTRY2(17, adVarChar, m_szemp_FirstName, sizeof(m_szemp_FirstName), lemp_FirstNameStatus, TRUE)  
  
      // Column FaxPhone is the 18th field in the table  
      ADO_VARIABLE_LENGTH_ENTRY2(18, adVarChar, m_szemp_Faxphone, sizeof(m_szemp_Faxphone), lemp_FaxphoneStatus, TRUE)  
  
      END_ADO_BINDING()  
  
public:  
   CHAR  m_szemp_LastName[21];  
   ULONG lemp_LastNameStatus;  
   CHAR  m_szemp_FirstName[11];  
   ULONG lemp_FirstNameStatus;  
   CHAR  m_szemp_Faxphone[25];  
   ULONG lemp_FaxphoneStatus;  
};  
  
// Function declarations  
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };  
void AttributesX();  
void PrintProviderError(_ConnectionPtr pConnection);  
void PrintComError(_com_error &e);  
  
int main() {  
   if ( FAILED(::CoInitialize(NULL)) )  
      return -1;  
   AttributesX();  
   ::CoUninitialize();  
}  
  
void AttributesX() {  
   // Define ADO object pointers.  Initialize pointers on define.  
   // These are in the ADODB::  namespace  
   _RecordsetPtr pRstEmployee  = NULL;  
   _ConnectionPtr pConnection = NULL;  
   FieldsPtr fldLoop = NULL;      
   PropertiesPtr proLoop = NULL;  
  
   // Define Other Variables  
   HRESULT hr = S_OK;  
   _variant_t Index;  
   Index.vt = VT_I2;  
   int j = 0;        
   // Open a recordset using a Client Cursor for the Employee Table  
   _bstr_t strCnn("Provider='sqloledb'; Data Source='(local)'; Initial Catalog='pubs'; Integrated Security='SSPI';");  
  
   try {  
      // open connection and record set  
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));  
      pConnection->Open(strCnn, "", "", adConnectUnspecified);  
  
      TESTHR(pRstEmployee.CreateInstance(__uuidof(Recordset)));  
      pRstEmployee->Open("Employee", _variant_t((IDispatch *)pConnection,true), adOpenForwardOnly,  
         adLockReadOnly, adCmdTable);  
  
      // Display the attributes of Connection.  
      printf("Connection attributes: %d \n", pConnection->Attributes);  
  
      // Display the attribute of the employee table's fields  
      printf("\nFields attributes:\n");  
      fldLoop = pRstEmployee->GetFields();  
  
      for (int i = 0 ; i < (int)fldLoop->GetCount() ; i++) {  
         Index.iVal = i;  
         printf ("   %s = %d \n", (LPSTR)fldLoop->GetItem(Index)->GetName(),  
            (int)fldLoop->GetItem(Index)->GetAttributes());  
      }  
  
      // Display Fields of the Employee table which are NULLBALE  
      printf("\nNULLABLE Fields :");  
  
      for (int i1 = 0 ; i1 < (int)fldLoop->GetCount() ; i1++) {  
         Index.iVal = i1;  
  
         if (fldLoop->GetItem(Index)->GetAttributes()  & adFldIsNullable)  
            printf ("%s  \n", (LPSTR)fldLoop->GetItem(Index)->GetName());      
      }  
  
      // Display the attributes of the Employee tables's  properties  
      printf("\nProperty attributes:\n");  
      proLoop = pRstEmployee->GetProperties();  
  
      for (int i2 = 0 ; i2 < (int)proLoop->GetCount() ; i2++) {  
         j = j + 1;  
         Index.iVal = i2;  
         printf (" %s = %d \n", (LPSTR)(_bstr_t)proLoop->GetItem(Index)->GetName(),  
            (int)proLoop->GetItem(Index)->GetAttributes());   
      }  
   }  
   catch(_com_error &e) {  
      // Notify the user of errors if any.  
  
      PrintProviderError(pConnection);  
      PrintComError(e);  
   }  
  
   // Clean up objects before exit.  
   if (pRstEmployee)  
      if (pRstEmployee->State == adStateOpen)  
         pRstEmployee->Close();  
   if (pConnection)  
      if (pConnection->State == adStateOpen)  
         pConnection->Close();  
}  
  
void PrintProviderError(_ConnectionPtr pConnection) {  
   // Print Provider Errors from Connection object.  
  
   // pErr is a record object in the Connection's Error collection.  
   ErrorPtr pErr = NULL;  
   long nCount = 0;      
   long i = 0;  
  
   if ( (pConnection->Errors->Count) > 0) {  
      nCount = pConnection->Errors->Count;  
  
      // Collection ranges from 0 to nCount -1.  
      for (i = 0 ; i < nCount ; i++) {  
         pErr = pConnection->Errors->GetItem(i);  
         printf("\t Error number: %x\t%s", (LPCSTR) pErr->Number, (LPCSTR) pErr->Description);  
      }  
   }  
}  
  
void PrintComError(_com_error &e) {  
   _bstr_t bstrSource(e.Source());  
   _bstr_t bstrDescription(e.Description());  
  
   // Print Com errors.    
   printf("\nError\n");  
   printf("Code = %08lx\n", e.Error());  
   printf("Code meaning = %s\n", e.ErrorMessage());  
   printf("Source = %s\n", (LPCSTR) bstrSource);  
   printf("Description = %s\n", (LPCSTR) bstrDescription);    
}
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Attributes and Name Properties Example (VC++)

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