PHP delete not working and displaying resulting table - php

Question

I'm having an issue where I have a drop down list which has owner's last name and once I select it and press delete button, it should remove the owners name from the drop down along with any associated owner information and boat information in mySQL database. I have written the #sql query to perform the delete function but doesn't seem to delete it.
Also how can I print out the tables (owner table and MarinaSlip table, these are the names in the mySQL database) once user click delete button. I want it to display both tables underneath in the same page.
deletedowner.php:
<?php #index.php for Assignment 10
$page_title = 'Assignment 10 for Marina Database';
include('header.html');
require('dbConn.php');
if ($_SERVER['REQUEST_METHOD'] == 'POST')
{
$id = $_POST['OwnerID'];
try
{
$sql = "DELETE m, o
FROM Owner AS o
LEFT JOIN MarinaSlip AS m
ON o.OwnerNum = m.OwnerNum
WHERE o.OwnerNum = :ownerId";
$stmt = $conn->prepare($sql);
$stmt->execute(array(':ownerId' => $id));
//include('DeletedUpdatedList.php'); when I put uncomment this line, it shows table but the delete button disappears
} // end try
catch (PDOException $e)
{
echo 'Error: '.$e->getMessage();
} //end catch
} //end if server
echo '<center>';
echo '<h3> Select the owners last name from drop down list to delete owner and their boats.</h3>';
$sql = "select OwnerNum, LastName from Owner"; //prints sql query
echo '<form action="Assignment10deleteowner.php" method="POST">';
echo "<select name='OwnerID' id=OwnerID'>";
foreach($conn->query($sql) as $row)
{
echo '<option value = "';
echo $row['OwnerNum'];
echo '"> ';
echo $row['LastName'];
echo '</option>';
} // end foreach
echo '</select>';
echo '<br><input type="submit" name="submit" value="Delete"> <br>';
echo '</form>'; //end form
// now to check if the delete button has been clicked
include('footer.html');
?>
DeletedUpdatedList.php
<?php #index.php for Assignment 10
$page_title = 'Assignment 10 for AlexaMara Marina Database';
echo '<h2> Updated list of Owners and MarinaSlip:</h2>';
$stmt = $conn->prepare("select * from Owner"); //prepare statment to print all of the owners
$stmt->execute(); //excute the sql query
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
$stmt = $conn->prepare("select * from MarinaSlip"); //prepare statment to print all of the owners
$stmt->execute(); //excute the sql query
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
echo "<table style='border: solid 1px black;'>"; //make table to display column headers
echo "<tr><th>OwnerNum</th><th>LastName</th><th>FirstName</th><th>Address</th><th>City</th><th>State</th><th>Zip</th></tr>";
class TableRows extends RecursiveIteratorIterator
{
function __construct($it) {
parent::__construct($it, self::LEAVES_ONLY);
}
function current() {
return "<td style='width:150px;border:1px solid black;'>" . parent::current(). "</td>";
}
function beginChildren() {
echo "<tr>";
}
function endChildren() {
echo "</tr>" . "\n";
}
}
foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v)
{
echo $v;
}
$conn = null;
echo "</table>"; //end table
//$sql = 'select BoatName, m.MarinaNum, SlipID from MarinaSlip s, Marina m where s.MarinaNum //= m.MarinaNum';
//echo '<form action="Assignment9.php" method="POST">';
//echo '</form>';
?>
[only prints 1 table and now formatting is messed up. The drop down and delete button should be first and then should display both tables][1]
Any help to do this would be much appreciated, thanks in advance

Answer 1

For numerous reasons, including protection from SQL injection, you should be using a prepared statement for your DELETE statement. You also must actually execute the statement for it to have any effect.
Here's the relevant portion of your code, modified to operate correctly:
if ($_SERVER['REQUEST_METHOD'] == 'POST')
{
$id = $_POST['OwnerID'];
try
{
$sql = "DELETE m, o
FROM Owner AS o
LEFT JOIN MarinaSlip AS m
ON o.OwnerNum = m.OwnerNum
WHERE o.OwnerNum = :ownerId";
$stmt = $conn->prepare($sql);
$stmt->execute(array(':ownerId' => $id));
} // end try
catch (PDOException $e)
{
echo 'Error: '.$e->getMessage();
} //end catch
} //end if server
By using a prepared statement, you gain automagic escaping, quoting and type-matching of variables.
Also, don't overcomplicate things. To get your tables to display,
$stmt = $conn->query('SELECT * FROM Owner');
echo '<table>';
while ($row = $stmt->fetch(PDO::FETCH_NUM))
{
echo '<tr>';
foreach ($row as $value)
{
echo "<td>{$value}</td>";
}
echo '</tr>';
}
echo '</table>';
should suffice. Change the query string for the MarinaSlip table as appropriate. Once that's working, then you can play with fancy formatting.

Answer 2

Execute the DELETE query to perform the deletion.
try
{
$sqlDel = "DELETE o, m
FROM Owner o
left join MarinaSlip m
on o.OwnerNum = m.OwnerNum
WHERE o.OwnerNum = '{$id}';" ;
$conn->query($sqlDel);
} // end try
catch (PDOException $e)
{
echo 'Error: '.$e->getMessage();
} //end catch
You can use inner join if both table will have data always