Display database search result in html using php? - php

Question

I'm attempting to create a page, where I can search for case files from my database, however, I can't get my code to work.
I already have pages showing all content of the database and where I can add new content.
I've read guides, tutorials and questions on stackoverflow, but can't find an answer on how to proceed.
I have the following php code in searchcasescript.php
<?php
$servername = "localhost";
$username = "test";
$password = "";
$dbname = "test";
$conn = mysqli_connect($servername, $username, $password, $dbname) or
die("connection failed: " . mysqli_connect_error());
mysqli_select_db($conn, $dbname) or die("something went wrong");
if(isset($_GET["form_submit"]))
{
$journalnummer =$_GET["journalnummer"];
$stmt = $conn->prepare("select * from testcases where journalnummer=? ");
$stmt->bind_param("s",$journalnummer);
$stmt->execute();
$val = $stmt->get_result();
$row_count= $val->num_rows;
if($row_count >0)
{
$result =$val->fetch_assoc();
print_r($result);
}
else{
echo "wrong number";
}
$stmt->close();
$conn->close();
}
?>
and my html:
<div class="container-fluid">
<div class="form-group">
<form action="searchcasescript.php" method="post">
<label for="journalnummer">Journalnummer:</label>
<input type="text" name="journal" class="form-control" required>
<div class="form-group"> <br>
<input type="submit" name="form_submit" class="btn btn-basic" value="Søg">
</form>
I've had different results depending on my changes to the php, but currently I'm getting nothing. Pressing search opens a new, blank page.
What I would like to end up with was being able to enter full or part of a case number and the search results being displayed on the same or a new page.
Can anyone point me in the right direction to read more about this and/or where to proceed with my code?
And apologies, if I've somehow missed the answer in one of the questions here.
UPDATED WITH "LIKE":
$stmt = $conn->prepare("SELECT * FROM straffesager WHERE journalnummer LIKE ?");
$stmt->bind_param("s", '%' . $journal . '%');

Answer 1

$journalnummer =$_GET["journalnummer"];
Your looking for journalnummer but your input has a name of journal
<input type="text" name="journal" class="form-control" required>
$_POST['journal'];
This is what should contain the number .