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Open and Close Methods Example (VC++)

This example uses the Open and Close methods on both Recordset and Connection objects that have been opened.

// Open_Close_Methods.cpp
// compile with: /EHsc
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")

#include <oledb.h>
#include <stdio.h>
#include <conio.h>
#include "icrsint.h"

// class extracts only fname,lastname and hire_date from employee table
class CEmployeeRs : public CADORecordBinding {
   BEGIN_ADO_BINDING(CEmployeeRs)

      // Column fname is the 2nd field in the table   
      ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_sze_fname, 
      sizeof(m_sze_fname), le_fnameStatus, FALSE)

      // Column lname is the 4th field in the table.
      ADO_VARIABLE_LENGTH_ENTRY2(4, adVarChar, m_sze_lname, 
      sizeof(m_sze_lname), le_lnameStatus, FALSE)

      // Column hiredate is the 8th field in the table.
      ADO_VARIABLE_LENGTH_ENTRY2(8, adDBDate,m_sze_hiredate, 
      sizeof(m_sze_hiredate), le_hiredateStatus, TRUE)

   END_ADO_BINDING()

public:
   CHAR   m_sze_fname[21];
   ULONG   le_fnameStatus;
   CHAR   m_sze_lname[31];
   ULONG   le_lnameStatus;
   DBDATE   m_sze_hiredate;
   ULONG   le_hiredateStatus;
};

// Function declarations
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void OpenX();
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

int main() {
   if ( FAILED(::CoInitialize(NULL)) )
      return -1;

   OpenX();
   ::CoUninitialize();
}

void OpenX() {
   // Define ADO object pointers.  Initialize pointers on define.
   // These are in the ADODB:: namespace
   _RecordsetPtr pRstEmployee = NULL;
   _ConnectionPtr pConnection = NULL;

   // Define string variables.
   _bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");

   IADORecordBinding *picRs = NULL;   // Interface Pointer declared.
   CEmployeeRs emprs;   // C++ Class object
   DBDATE varDate;

   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), 
         adOpenKeyset, adLockOptimistic, adCmdTable);

      // Open an IADORecordBinding interface pointer for Binding Recordset to a class.
      TESTHR(pRstEmployee->QueryInterface(__uuidof(IADORecordBinding),(LPVOID*)&picRs));

      // Bind the Recordset to a C++ Class here.
      TESTHR(picRs->BindToRecordset(&emprs));

      // Assign first employee record's hire date to variable, then change hire date.
      varDate = emprs.m_sze_hiredate;
      printf("Original data\n");
      printf("\tName - Hire Date\n");
      printf("  %s  %s - %d/%d/%d\n\n",
         emprs.le_fnameStatus == adFldOK ? 
         emprs.m_sze_fname : "<NULL>",
         emprs.le_lnameStatus == adFldOK ? 
         emprs.m_sze_lname : "<NULL>",
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.month : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.day : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.year : 0); 

      emprs.m_sze_hiredate.year = 1900;
      emprs.m_sze_hiredate.month = 1;
      emprs.m_sze_hiredate.day = 1;
      picRs->Update(&emprs);

      printf("\nChanged data\n");
      printf("\tName - Hire Date\n");
      printf("  %s %s - %d/%d/%d\n\n",
         emprs.le_fnameStatus == adFldOK ? 
         emprs.m_sze_fname : "<NULL>",
         emprs.le_lnameStatus == adFldOK ? 
         emprs.m_sze_lname : "<NULL>",
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.month : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.day : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.year : 0); 

      // Requery Recordset and reset the hire date.
      pRstEmployee->Requery(adOptionUnspecified);

      // Open IADORecordBinding interface pointer for Binding Recordset to a class.
      TESTHR(pRstEmployee->QueryInterface(__uuidof(IADORecordBinding), (LPVOID*)&picRs));

      // Rebind the Recordset to a C++ Class here.
      TESTHR(picRs->BindToRecordset(&emprs));
      emprs.m_sze_hiredate = varDate;
      picRs->Update(&emprs);
      printf("\nData after reset\n");
      printf("\tName - Hire Date\n");
      printf("  %s %s - %d/%d/%d", emprs.le_fnameStatus == adFldOK ? 
         emprs.m_sze_fname : "<NULL>",
         emprs.le_lnameStatus == adFldOK ? 
         emprs.m_sze_lname : "<NULL>",
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.month : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.day : 0,
         emprs.le_hiredateStatus == adFldOK ? 
         emprs.m_sze_hiredate.year : 0); 
   }
   catch(_com_error &e) {
      // Display errors, if any. Pass a connection pointer accessed from the Connection.
      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;

   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("\t Error number: %x\t%s", pErr->Number, pErr->Description);
      }
   }
}

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);
}
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