How can I populate a 3rd column result on intersections of 1st and 2nd columns all from the same table that are selected by the user on dropdown?

Question

I have a column vehicle_name and I would like 2 dropdown lists of my 2 other columns namely, vehicle_type and vehicle_color. When these 2 dropdown values are selected and submitted, I would like their intersection to print out the values from vehicle_name. So far my code only generates a dropdown list for vehicle_type, I would need another dropdown for vehicle_colour. Which on submissions populates the intersected values for the vehicle_name. How can I achieve this?

<!DOCTYPE html>
<html>
<body>
<?php
echo "<br>";
echo "<br>";
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "mydb";


$db = new mysqli($servername, $username, $password, $dbname);


if (!$db) {
    exit('Connect Error (' . mysqli_connect_errno() . ') '
        . mysqli_connect_error());
}
?>

<br>
<div class="label">Select vehicle type:</div>

<select name="payment_method">
    <option value = "">---Select---</option>
<?php
$queryusers = "SELECT DISTINCT vehicle_type FROM orders";
$db = mysqli_query($db, $queryusers);
while ($d=mysqli_fetch_assoc($db)) {
    echo "<option value='{".$d['vehicle_type']."}'>".$d['vehicle_type']."</option>";
}

?>
</select>


<br>
<div class="label_for_time">Select color:</div>

<select name="vehicle_color">
    <option value = "">---Select---</option>

<?php
$query_for_color = "SELECT DISTINCT vehicle_color FROM orders";
$db = mysqli_query($db, $query_for_date);
while ($a=mysqli_fetch_assoc($db)) {
    echo "<option value='{".$a['vehicle_color']."}'>".$a['vehicle_color']."</option>";
}

?>
</select>
<br>
<br>


<button class="go-btn" type="submit">Go</button>
</body>
</html>

Answer 1

As I don't see any AJAX / client-side code in your above example I assume that this is a pure backend-side filtering you are performing. Your code is currently missing parts of the required elements we would need but let's try to figure this out together:

1. Form around your inputs

Add a <form method="POST" target="path-to-your-script.php"> where "path-to-your-script.php" has to be changed to your PHP file name or rewritten URL path. This has to be around the <select> boxes.

You may also use PHP_SELF to set this automatically, this should work in most cases. I used html_entities($var) to avoid any code injections via manipulated URL.

<form name="test" action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">

2. Check for POST'ed variable 'vehicle_type'

In your form, check if a search for available colors has been performed:

<?php
  $query_for_color = "SELECT DISTINCT vehicle_color FROM orders";

  // check if the form variable 'vehicle_type' is available; if so, filter entries.
  if (isset($_POST['vehicle_type'])) {
    $vType= filter_var($_POST['vehicle_type'], FILTER_SANITIZE_STRING);
    $query_for_colors .= ' WHERE vehicle_type = \''.$vType.'\'';
  } 
  $db = mysqli_query($db, $query_for_date);
  while ($a=mysqli_fetch_assoc($db)) {
      echo "<option value='{".$a['vehicle_color']."}'>".$a['vehicle_color']."</option>";
  }
?>

Edit:

As pointed out by one user in the comment, filter_var($var, FILTER_SANITIZE_STRING) won't be enough to avoid potential SQL injections. This was just a recommendation and was not part of the question at all. If you have to work with user data, do more than using filter_var(), instead use either prepared statements or properly escape the user data. There are many tutorials like this one out there that will guide you to safe queries.

How can I populate a 3rd column result on intersections of 1st and 2nd columns all from the same table that are selected by the user on dropdown?

Question

1 answers

solution1
0 ACCPTED 2019-05-23 14:21:01

How can I populate a 3rd column result on intersections of 1st and 2nd columns all from the same table that are selected by the user on dropdown?

Question

1 answers

solution1 0 ACCPTED 2019-05-23 14:21:01

solution1
0 ACCPTED 2019-05-23 14:21:01