<?php
  $host = "localhost";
  $user = "root";
  $password = "";
  $dbname = "henry";
  $con=mysqli_connect($host, $user, $password, $dbname);
  if (mysqli_connect_errno()) {
    echo "Failed to connect to MariaDB: " . mysqli_connect_error();
    exit;
  }

    $query = "SELECT CONCAT(T1.Title, ' - ', T2.Title) AS Titles
              FROM book T1 JOIN book T2 ON T1.Price = T2.Price
              AND T1.Title > T2.Title
              AND T1.PublisherCode = T2.PublisherCode";
    $result = mysqli_query($con, $query);
    if (!$result) {
      print ( "Could not successfully run query ($querystring) from DB: " . mysqli_error($con));
      exit;
    }

    if (mysqli_num_rows($result) == 0) {
      print ("No branch found for branch number: $branchNum");
      exit;
    }

    while($row = mysqli_fetch_array($result)){
      print($row['Titles']);
      echo '<br/>';
    }

?>