I am testing a simple PHP-MySQL script, and it’s to delete one record from the table. The strange thing is in this block of code:
// Check if the form has been submitted:
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
if ($_POST['sure'] == 'Yes') { // Delete the record.
// Make the query:
$q = "DELETE FROM users WHERE user_id=$id LIMIT 1";
$r = @mysqli_query ($dbc, $q);
if (mysqli_affected_rows($dbc) == 1) { // If it ran OK.
When I use NetBeans to debug this script, after the record is deleted($r = @mysqli_query ($dbc, $q) is executed), the affected_rows = 1 in the variable section of NetBeans, which is correct. But then after I press F7 to step into and ‘if (mysqli_affected_rows($dbc) == 1)’ is executed, affected_rows suddenly becomes -1, and the program logic jumps to the error reporting branch.
If I don’t debug and just run the script, the Deletion is totally OK. What’s the possible cause?
Here’s the whole script:
<?php # Script 10.2 - delete_user.php
// This page is for deleting a user record.
// This page is accessed through view_users.php.
$page_title = 'Delete a User';
include ('includes/header.html');
echo '<h1>Delete a User</h1>';
// Check for a valid user ID, through GET or POST:
if ( (isset($_GET['id'])) && (is_numeric($_GET['id'])) ) { // From view_users.php
$id = $_GET['id'];
} elseif ( (isset($_POST['id'])) && (is_numeric($_POST['id'])) ) { // Form submission.
$id = $_POST['id'];
} else { // No valid ID, kill the script.
echo '<p class="error">This page has been accessed in error.</p>';
include ('includes/footer.html');
exit();
}
require ('./mysqli_connect.php');
// Check if the form has been submitted:
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
if ($_POST['sure'] == 'Yes') { // Delete the record.
// Make the query:
$q = "DELETE FROM users WHERE user_id=$id LIMIT 1";
$r = @mysqli_query ($dbc, $q);
if (mysqli_affected_rows($dbc) == 1) { // If it ran OK.
// Print a message:
echo '<p>The user has been deleted.</p>';
} else { // If the query did not run OK.
echo '<p class="error">The user could not be deleted due to a system error.</p>'; // Public message.
echo '<p>' . mysqli_error($dbc) . '<br />Query: ' . $q . '</p>'; // Debugging message.
}
} else { // No confirmation of deletion.
echo '<p>The user has NOT been deleted.</p>';
}
} else { // Show the form, to confirm that this user should be deleted.
// Retrieve the user's information:
$q = "SELECT CONCAT(last_name, ', ', first_name) FROM users WHERE user_id=$id";
$r = @mysqli_query ($dbc, $q);
if (mysqli_num_rows($r) == 1) { // Valid user ID, show the form. (Just 1 result as user_id is PK)
// Get the user's information:
$row = mysqli_fetch_array ($r, MYSQLI_NUM);
// Display the record being deleted:
echo "<h3>Name: $row[0]</h3>
Are you sure you want to delete this user?";
// Create the form:
echo '<form action="delete_user.php" method="post">
<input type="radio" name="sure" value="Yes" /> Yes
<input type="radio" name="sure" value="No" checked="checked" /> No
<input type="submit" name="submit" value="Submit" />
<input type="hidden" name="id" value="' . $id . '" />
</form>';
} else { // Not a valid user ID.
echo '<p class="error">This page has been accessed in error.</p>';
}
} // End of the main submission conditional.
mysqli_close($dbc);
include ('includes/footer.html');
?>
Another problem is that after running the script, there are many lines of warnings:
Warning: main(): Couldn't fetch mysqli in C:\\xampp\\htdocs\\phpmysql4_working\\delete_user.php on line 75
Warning: main(): Couldn't fetch mysqli in C:\\xampp\\htdocs\\phpmysql4_working\\includes\\footer.html on line 11
Call Stack
# Time Memory Function Location
1 0.1000 146128 {main}( ) ..\\delete_user.php:0
2 249.5054 187032 include( 'C:\\xampp\\htdocs\\phpmysql4_working\\includes\\footer.html' ) ..\\delete_user.php:75
But MySQL was actually been accessed successfully. The footer.html is:
<!-- End of the page-specific content. --></div>
<div id="footer">
<p>Copyright © <a href="#">Plain and Simple</a> 2007 |
Designed by <a href="http://www.edg3.co.uk/">edg3.co.uk</a> |
Sponsored by <a href="http://www.opendesigns.org/">Open Designs</a> |
Valid <a href="http://jigsaw.w3.org/css-validator/">CSS</a> & <a href="http://validator.w3.org/">XHTML</a></p>
</div>
</body>
</html>