Ejemplo de la propiedad Sort (VC++)

Se aplica a: Access 2013, Office 2013

En este ejemplo se usa la propiedad Sort del objeto Recordset para reordenar las filas de un objeto Recordset derivado de la tabla Authors de la base de datos Pubs. Una rutina de la utilidad secundaria imprime cada fila.

 
// BeginSortCpp 
#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 SortX(void); 
void SortXprint(_bstr_t title, _RecordsetPtr rstp); 
void PrintProviderError(_ConnectionPtr pConnection); 
void PrintComError(_com_error &e); 
 
////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 SortX(); 
 
 ::CoUninitialize(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// SortX Function // 
// // 
////////////////////////////////////////////////////////// 
void SortX(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace. 
 _ConnectionPtr pConnection = NULL; 
 _RecordsetPtr pRstAuthors = NULL; 
 
 // Define string variables. 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "Initial Catalog='pubs';Integrated Security='SSPI';"); 
 
 try 
 { 
 TESTHR(pConnection.CreateInstance(__uuidof(Connection))); 
 
 TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset))); 
 
 pRstAuthors->CursorLocation = adUseClient; 
 pConnection->Open (strCnn, "", "", adConnectUnspecified); 
 pRstAuthors->Open("SELECT * FROM authors", 
 _variant_t((IDispatch *) pConnection), 
 adOpenStatic, adLockReadOnly, adCmdText); 
 
 SortXprint(" Initial Order ", pRstAuthors); 
 
 //Clear the screen for the next display. 
 printf("\nPress any key to continue..."); 
 getch(); 
 system("cls"); 
 
 pRstAuthors->Sort = "au_lname ASC, au_fname ASC"; 
 SortXprint("Last Name Ascending", pRstAuthors); 
 
 //Clear the screen for the next display. 
 printf("\nPress any key to continue..."); 
 getch(); 
 system("cls"); 
 
 pRstAuthors->Sort = "au_lname DESC, au_fname ASC"; 
 SortXprint("Last Name Descending", pRstAuthors); 
 } 
 catch(_com_error &e) 
 { 
 PrintProviderError(pConnection); 
 PrintComError(e); 
 } 
 
 // Clean up objects before exit. 
 if (pRstAuthors) 
 if (pRstAuthors->State == adStateOpen) 
 pRstAuthors->Close(); 
 if (pConnection) 
 if (pConnection->State == adStateOpen) 
 pConnection->Close(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// SortXprint Function // 
// // 
////////////////////////////////////////////////////////// 
//This is the secondary utility routine that prints 
//the given title, and the contents of the specified Recordset. 
void SortXprint(_bstr_t title, _RecordsetPtr rstp) 
{ 
 printf("---------------%s---------------\n", (LPCSTR)title); 
 printf("First Name Last Name\n" 
 "---------------------------------------------------\n"); 
 rstp->MoveFirst(); 
 int intLineCnt = 4; 
 while (!(rstp->EndOfFile)) 
 { 
 _bstr_t aufname; 
 _bstr_t aulname; 
 aufname = rstp->GetFields()->GetItem("au_fname")->Value; 
 aulname = rstp->GetFields()->GetItem("au_lname")->Value, 
 printf("%s %s\n",(LPCSTR) aufname, (LPCSTR) aulname); 
 rstp->MoveNext(); 
 intLineCnt++; 
 if (intLineCnt % 20 ==0) 
 { 
 printf("\nPress any key to continue...\n"); 
 getch(); 
 } 
 } 
} 
 
////////////////////////////////////////////////////////// 
// // 
// 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); 
 
} 
 
// EndSortCpp