include ('./functions/sanitise.inc'); // include the functions to prevent an SQL injection attack.

if (isset($_POST['submit'])) { // If the Login button is clicked.

    $strMessage = NULL;
    $strUserError = NULL; 
    $strPassError = NULL;

    // Check for a username.
    // If not found, return an error message.
    if (empty($_POST['log_username'])) {
      $strUsername = FALSE;
      $strUserError .= 'Please enter your username.';
    } else {
      $strUsername = $_POST['log_username'];
    }
    
    // Check for a password.
    // If not found, return an error message.
    if (empty($_POST['log_password'])) {
      $strPassword = FALSE;
      $strPassError .= 'Please enter your password.';
    } else {
      $strPassword = $_POST['log_password'];
    }
    
    // If the user/pass combination is filled out, handle the form.
    if ($strUsername && $strPassword) {
      require_once ('../sql_connect.php'); // Connect to the db.
      // Check that the username select is not already taken.
      $sqlQuery = sprintf ("SELECT TOP 10000 username, password FROM km_users WHERE username='" . sanitize($strUsername, SQL) . "' ORDER BY username");
      $varResult = odbc_exec($dbc, $sqlQuery);
      if (odbc_num_rows($varResult) == 0) { // if $count is 0, then there were no rows with the selected username.
        $strUserError = 'Invalid Username.  Please check your username again.';
        odbc_close($dbc); // Close the db connection.
      } else { // If the username is in the database, check the password.
        $sqlQuery = sprintf ("SELECT TOP 10000 username, password, firstname FROM km_users WHERE (username='" . sanitize($strUsername, SQL) . "' AND password='" . sanitize($strPassword, SQL) . "') ORDER BY username");
        $varResult = odbc_exec($dbc, $sqlQuery);
        if (odbc_num_rows($varResult) == 0) { // if $count is 0, then there were no rows with the selected username.
            $strPassError = 'Your Username and Password do not match.  Please check your password.';
            odbc_close($dbc); // Close the db connection.
        } else {

//////////////////////
// Here's where I'm having the problem.  I want to see this data 
// (so I know what I'm pulling is correct).  The example I'm learning 
// from here uses MYSQL, so they use MYSQL_NUM.  What can I use here, 
// so that the echo statement below shows the username pulled from the 
// SELECT statement?
//
// MSSQL_NUM isn't supported on my installation of PHP (hence why I'm 
// using ODBC), and ODBC_NUM isn't a defined constant.
//////////////////////

          $row = odbc_fetch_array($varResult, MYSQL_NUM);
          echo $row[1];

          odbc_close($dbc); // Close the db connection.
          exit(); // exit the script
        }
      }
    }
} // end of main if conditional.

// Set the page title and include the header.
$strPageTitle = 'Login';
include ('./header.inc');

?>... (html follows: standard login form, username/password)