PHP form submit with SQL query results in blank table? - php

Question

I've currently got a page with a form, and I'd like to populate a table based off a SQL query using a variable. I know the value from the select dropdown is being extracted correctly, and I believe I've got bindValue implemented correctly. However, upon submitting the form, nothing shows up in the table. I know the SQL statement is correct as well, as I've run it directly in MySQL and gotten the results I'm looking for.
Here's my code currently:
echo '<form align="center" method="post">';
echo '<select name="flightSelect">';
$flightstmt = $conn->query('select * from flight');
$flightstmt->execute();
while($row = $flightstmt->fetch(PDO::FETCH_ASSOC))
{
echo "<option value='".$row['flightnum']."'>";
echo $row['origination']."->".$row['destination'];
echo '</option>';
}
echo '</select>';
echo '<table>';
if (isset($_POST['flightSelect']))
{
$flightSelect = $_POST['flightSelect'];
$flightPassengers = $conn->prepare('select * from passenger where passnum in (select passnum from manifest where flightnum=:flightSelect)');
$flightPassengers->bindValue(':flightSelect', $flightSelect, PDO::PARAM_INT);
$flightPassengers->execute();
while($row = $flightPassengers->fetch(PDO::FETCH_ASSOC))
{
echo '<tr>';
echo '<td>';
echo $row['lastname']." ".$row['firstname'];
echo '</td>';
echo '</tr>';
}
}
echo '</table>';
echo '<input type="submit" name="submit" value="Find passengers on this flight">';
echo '</form>';
Thanks in advance for any feedback!

Answer 1

<form align="center" method="post"> Form lacks action attribute.

Answer 2

Open the Network Panel in Chrome DevTools and check if the HTTP status code is 500
if yes, then check the error log, you'll find the stack trace atleast.

Answer 3

You need to verify that the passenger table should have flight data you select while submitting.
Debug the query by removing flight condition and see are you get the result for flight.
Rest of the code is correct