PHP produces blank screen with submit button click - php

Question

Below I have code that is supposed to update an entry in the database. When I click the submit button the form goes away but it is not replaced with anything and more importantly it doesn't update the database. I cannot seem to find where the error is and any help would be greatly appreciated.
<?php
define('TITLE', 'Quotes Entry!');
// Include the header:
include('header.php');
include('mysqli_connect.php');
// Leave the PHP section to display lots of HTML:
?>
<?php //
mysqli_set_charset($dbc, 'utf8');
if (isset($_GET['id']) && is_numeric($_GET['id']) ) { // Display the entry in a form:
// Define the query:
$query = "SELECT title, entry FROM Salinger WHERE entry_id={$_GET['id']}";
if ($r = mysqli_query($dbc, $query)) { // Run the query.
$row = mysqli_fetch_array($r); // Retrieve the information.
//make the form
print '<form action = "edit_entry.php" method = "post">
<p> Entry Titles <input type= "text" name = "title" size = "40" maxsize = "100" value = "' . htmlentities($row['title']) . '" /></p>
<p>Entry Text <textarea name = "entry" cols = "40" rows = "5">'. htmlentities($row['entry']).'</textarea></p>
<input type = "hidden" name = "id" value = "'.$_GET['id'] .'" />
<input type = "submit" name = "submit" value = "Update This Entry!" />
</form>';
} else { // Couldn't get the information.
print '<p style="color: red;">Could not retrieve the blog entry because:<br />' . mysqli_error($dbc) . '.</p><p>The query being run was: ' . $query . '</p>';
}
} elseif (isset($_POST['id']) && is_numeric($_POST['id'])) { // Handle the form.
$problem = "false";
if(!empty($_POST['title']) && !empty($_POST['entry'])){
$title = mysqli_real_escape_string($dbc, trim(strip_tags($_POST['title'])));
$entry = mysqli_real_escape_string($dbc, trim(strip_tags($_POST['entry'])));
} else{
print '<p style="color: red;">Could not retrieve the blog entry because:<br />' . mysqli_error($dbc) . '.</p><p>The query being run was: ' . $query . '</p>';
$problem = true;
}
if(!problem){
$query = "UPDATE Salinger SET title = '$title', entry = '$entry' WHERE entry_id = {$_POST['id']}";
$r = mysqli_query($dbc, $query); //execute the query
if(mysqli_affected_rows($dbc) == 1){
print'<p> The blog entry has been updated.</p>';
// Report on the result:
} else {
print '<p style="color: red;">Could not retrieve the blog entry because:<br />' . mysqli_error($dbc) . '.</p><p>The query being run was: ' . $query . '</p>';
}
}
} else{
print '<p style="color: red;">Could not retrieve the blog entry because:<br />' . mysqli_error($dbc) . '.</p><p>The query being run was: ' . $query . '</p>';
}
mysqli_close($dbc); // Close the database connection.
include('footer.php'); // Need the footer.
?>

Answer 1

Because you set $problem = "false"; you need to set it to $problem= false;
"false" is not false
And !problem should be !$problem

Answer 2

You have a problem with GET[id].
It's getting blank cause of POST event on screen, due to which your SQL is not finding the record.
To test assign hard coded value in your select statement.
Example
$query = "SELECT title, entry FROM Salinger WHERE entry_id=10";