Ejemplo de propiedades Attributes y Name (VC++)
En este ejemplo se muestra el valor de la propiedad Attributes para los objetos Connection, Field y Property. Usa la propiedad Name para mostrar el nombre de cada objeto Field y Property.
// 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);
}
Consulte también
Propiedad Attributes (ADO)
Objeto de conexión (ADO)
Objeto Field
Propiedad Name (ADO)
Objeto Property (ADO)