Multiple Fields search MySQL database using php

I’m almost there, my code it doesn’t show any results.
it’s a basic form where users search by postcode and property type.
they should be able to search by entering only the postcode or both.
I’m working in localhost php7
here the html

<form action="phpSearch.php" method="post">
    <input type="text" placeholder="Search" name="postcode" id="postcode">
    <select name="type" id="type">
        <option value="Terraced">Terraced</option>
        <option value="Detached">Detached</option>
    </select>
    <button type="submit" name="submit">Search</button>
</form>

here the php

<?php
$postcode = $_POST['postcode'];
$type = $_POST['type'];


$servername = "localhost";
$username = "root";
$password = "";
$db = "priceverification";

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

if ($conn->connect_error){
    die("Connection failed: ". $conn->connect_error);
}

$sql = "SELECT * from house WHERE $type like '%$postcode%'";

$result = $conn->query($sql);
  if($result){
if ($result->num_rows > 0){
while($row = $result->fetch_assoc()){
    echo $row["postcode"]."  ".$row["type"]."  ".$row["town"]."<br>";
}
} else {
    echo "0 records";
}
 }else {
                echo "<br> Database error.";
            }
$conn->close();
?>

database here

Answer

$type like '%$postcode%' is invalid code for multiple reasons. You need to build the search criteria based on the values coming from the form.

Here is how the code should look like properly:

<?php

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$conn = new mysqli("localhost", "root", "", "priceverification");
$conn->set_charset('utf8mb4'); // always set the charset

$postcode = $_POST['postcode'] ?? '';
$type = $_POST['type'] ?? '';

$wheres = [];
$values = [];
if ($postcode) {
    $wheres[] = 'postcode LIKE ?';
    $values[] = '%'.$postcode.'%';
}
if ($type) {
    $wheres[] = 'type = ?';
    $values[] = $type;
}
$where = implode(' AND ', $wheres);
if ($where) {
    $sql = 'SELECT * from house WHERE '.$where;
} else {
    $sql = 'SELECT * from house';
}

$stmt = $conn->prepare($sql);
$stmt->bind_param(str_repeat('s', count($values)), ...$values);
$stmt->execute();
$result = $stmt->get_result();

if ($result->num_rows > 0) {
    foreach ($result as $row) {
        echo $row["postcode"] . "  " . $row["type"] . "  " . $row["town"] . "<br>";
    }
} else {
    echo "0 records";
}