How do I use and execute queries on database in my native C++ windows application.

#define DBNTWIN32
#include <stdio.h>
#include <windows.h>
#include <sqlfront.h>
#include <sqldb.h>

// Forward declarations of the error handler and message handler. 

int err_handler(PDBPROCESS, INT, INT, INT, LPCSTR, LPCSTR);
int msg_handler(PDBPROCESS, DBINT, INT, INT, LPCSTR, LPCSTR,
LPCSTR, DBUSMALLINT);
main()
{
   PDBPROCESS dbproc; // The connection with SQL Server. 
   PLOGINREC login; // The login information. 
   DBCHAR name[100];
   DBCHAR city[100];

// Install user-supplied error- and message-handling functions.

   dberrhandle (err_handler);
   dbmsghandle (msg_handler);

// Initialize DB-Library.

   dbinit ();

// Get a LOGINREC.

   login = dblogin ();
   DBSETLUSER (login, "my_login");
   DBSETLPWD (login, "my_password");
   DBSETLAPP (login, "example");

// Get a DBPROCESS structure for communication with SQL Server. 

   dbproc = dbopen (login, "my_server");

// Retrieve some columns from the authors table in the
// pubs database.
// First, put the command into the command buffer. 

   dbcmd (dbproc, "SELECT au_lname, city FROM pubs..authors");
   dbcmd (dbproc, " WHERE state = 'CA' ");

// Send the command to SQL Server and start execution. 

   dbsqlexec (dbproc);

// Process the results. 

   if (dbresults (dbproc) == SUCCEED)
   {

// Bind column to program variables. 

      dbbind (dbproc, 1, NTBSTRINGBIND, 0, name);
      dbbind (dbproc, 2, NTBSTRINGBIND, 0, city);

// Retrieve and print the result rows. 

      while (dbnextrow (dbproc) != NO_MORE_ROWS)
      {
         printf ("%s from %s\n", name, city);
      }
   }

// Close the connection to SQL Server. 

   dbexit ();
   return (0);
}

int err_handler (PDBPROCESS dbproc, INT severity,
INT dberr, INT oserr, LPCSTR dberrstr, LPCSTR oserrstr)
{
   printf ("DB-Library Error %i: %s\n", dberr, dberrstr);
   if (oserr != DBNOERR)
   {
      printf ("Operating System Error %i: %s\n", oserr, oserrstr);
   }
   return (INT_CANCEL);
}

int msg_handler (PDBPROCESS dbproc, DBINT msgno, INT msgstate,
INT severity, LPCSTR msgtext, LPCSTR server,
LPCSTR procedure, DBUSMALLINT line)
{
   printf ("SQL Server Message %ld: %s\n", msgno, msgtext);
   return (0);
}
</sqldb.h></sqlfront.h></windows.h></stdio.h>

#include <dbmanager.h>
#include <iostream>

using namespace std;

using namespace oracle::occi;

const string sqlString("select empno, ename, hiredate from emp");

const string dateFormat("DD-MON-YYYY HH24:MI:SS");

int main(int argc, char **argv)
{
  if (argc != 2)
  {
	cerr << "\nUsage: " << argv[0] << " <db-user-name>\n" << endl;
	exit(1);
  }

  string userName = argv[1];

  // Initialize OracleServices

  DbManager* dbm = NULL;

  OracleServices* oras = NULL;

  Statement *stmt = NULL;

  ResultSet *resultSet = NULL;

  try

  {

	// Obtain OracleServices object with the default args.

	// The default args creates OracleServices with an environment of

	// Environment::OBJECT|Environment::THREADED_MUTEXED

	dbm = new DbManager(userName);

	oras = dbm->getOracleServices();

	// Obtain a cached connection

	Connection * conn = oras->connection();

	// Create a statement

	stmt = conn->createStatement(sqlString);

	int empno;

	string ename;

	Date hireDate;

	string dateAsString;

	// Execute query to get a resultset

	resultSet = stmt->executeQuery();

	while (resultSet->next()) 
	{
	  empno = resultSet->getInt(1);  // get the first column returned by the query;

	  ename = resultSet->getString(2);  // get the second column returned by the query

	  hireDate = resultSet->getDate(3);  // get the third column returned by the query

	  dateAsString="";

	  //You cannot check for null until the data has been read

	  if (resultSet->isNull(1))

	  {

				cout << "Employee num is null... " << endl;

	  }

	  if (resultSet->isNull(2))

	  {

				cout << "Employee name is null..." << endl;

	  }

	  if (resultSet->isNull(3))

	  {

				cout << "Hire date is null..." << endl;

	  }
	  else
	  {
				dateAsString=hireDate.toText(dateFormat);
	  }

	  cout << empno << "\t" << ename << "\t" << dateAsString << endl;

	}

	// Close ResultSet and Statement

	stmt->closeResultSet(resultSet);

	conn->terminateStatement(stmt);
 

	// Close Connection and OCCI Environment

	delete dbm;

  }

  catch (SQLException& ex)

  {

	if (dbm != NULL)

	{
		dbm->rollbackActions(ex, stmt, resultSet); // free resources and rollback transaction

	}

  }

  
  return 0;

}</db-user-name></iostream></dbmanager.h>