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Hi,

Old novice I am - confused and frustrated I'm getting.

I see the following error: Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\XAMPP\xampp\htdocs\websitename\edit_user.php on line 91

 

This happens in scripts 9.2 and 9.3 when they are called from script 9.1 I can't tell if this is because I think I'm talking to the database and I'm not, or if there's something about the setup I have of XAAMP - which I kind of doubt - or if there's something wrong with script 9.1. That's why I didn't initially post the code - cause I don't know what'd be helpful. I have looked over the code in 9.1 and 9.2 with a fine tooth comb. Found mistakes but nothing that fixed this error.

 

What causes mysqli_num_rows() to return a boolean? I have been searching everywhere. Did I miss something in Larry's explanation? I'm sure it's right in front of me ... I'll be dayng-ed if I can find it!

 

Help - and Thanks!

 

 

Mike

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Normally I'd be inclined to say that something your doing query wise with the database isn't returning any result resource.

 

Are you calling the query and using the @ to suppress error messages?

 

Just post the code anyway, probably be quicker.

Edited by Jonathon

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Thanks Jonathon,

 

Yes I am using the @ error suppressor - that's what's in the book. Should I remove it?

 

Thank you so much!

 

Here's the code:

 

<?php # Script 9.3 - edit_user.php

 

// This page is for editing a user record.

// This page is accessed through view_users.php

 

$page_title = 'Edit a User';

include('includes/header.htm');

 

echo '<h1>Edit 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, kell the script.

echo '<p class="error">This page has been accessed in error.</p>';

include('includes/footer.html');

exit();

}

 

require_once('../called_functions/mysqli_connect.php');

 

// Check if the form has been submitted:

if (isset($_POST['submitted'])) {

 

$errors = array();

 

// Check for a first name:

if(empty($_POST['first_name'])) {

$errors[] = 'You forgot to enter your first name.';

} else {

$fn = mysqli_real_escape_string($dbc, trim($_POST['first_name']));

}

 

// Check for the last name:

if(empty($_POST['last_name'])) {

$errors[] = 'You forgot to enter your last name.';

} else {

$ln = mysqli_real_escape_string($dbc, trim($_POST['email']));

}

 

// Check for an email address:

if (empty($_POST['email'])) {

$errors[] = 'You forgot to enter your email address';

} else {

$ln = mysqli_real_escape_string($dbc, trim($_POST['email']));

}

 

if (empty($errors)) { // If everything is ok

 

// Test for unique email addresses:

$q = "SELECT user_id FROM users WHERE email = '$e' AND user_id != $id";

$r = @mysqli_query($dbc, $q);

if (mysqli_num_rows($r) == 0) {

 

// Make query

$q = "UPDATE users SET first_name='$fn', last_name='$ln', email='$e' 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 edited.</p>';

 

} else { // If it did not run OK

echo'<p class="error">The user could not be edited due to a system error. We apologize for any inconvenience.</p>'; // Public message

echo '<p>' . mysqli_error($dbc) . '<br />Query: ' . $q . '</p>'; // Debugging message.

}

 

} else {

echo '<p class="error">That email address has already been registered</p>';

}

 

} else {

 

echo '<p class="error">The following error(s) occurred:<br />';

foreach ($errors as $msg) { // Print each error.

echo" - #msg<pr /> \n";

}

echo '</p><p>Please try again.</p>';

 

} // End if if (empty($errors)) IF.

 

} //End of submit conditional.

 

// Always show the form ...

 

// Retrieve the user's information"

$q = "SELECT first_name, last_name, email, FROM users WHERE user_id=$id";

$r = @mysqli_query ($dbc, $q);

 

if (mysqli_num_rows($r) == 1) { // Valid user ID, show the form.

 

// Get the user's information:

$row = mysqli_fetch_array ($r, MYSQLI_NUM);

 

// Create the form

echo '<form action="edit_user.php" method = "post">

<p>First Name: <input type = "text" name ="first_name" size="15" maxlenght="15" value="' . $row[0] . '" /></p>

<p>Last Name: <input type="text" name="last_name" size="15" maxlength="30" value="' . $row[1] . '" /></p>

<p>Email Address: <input type = "text" name="email" size="20" maxlength="40" value="'.$row[2] . '" ?> </p>

<p><input type="submit" name="submit" value="Submit" /></p>

<input type=:hidden" name="submitted" value="TRUE" />

<input type="hidden" name="id" value="' . $id . '" />

</form>';

 

} else {

echo'<p class="error">This page has been accessed in error.</p>';

}

 

mysqli_close($dbc);

 

include('includes/footer.html');

?>

 

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Yes! Thank You. Same problem in the other script too.

 

if (You can find that code error -> on your phone!!!!) {

echo "Maybe you can help me find the next error";

} however {

I'll try and figure it out myself first

}

 

Thanks!!!

 

You - are a prince! Thanks

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Hi Jonathon,

The error for the 9.2 script is:

 

The user could not be deleted due to a system error.

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 1' at line 1

Query: DELETE FROM users WHERE user_id= LIMIT 1

 

What's odd is that if I run the script and echo the variable $id right after the first isset conditional, it is empty. However, it exists everywhere else. Since $id is empty, the query fails and presents that error. I can echo $id in every part of the code and it's there, except after those conditionals.

 

Thanks in advance!

 

the code is:

 

<?php # Script 9.2 - 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.htm');

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 = $_GET['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_once('../called_functions/mysqli_connect.php');

 

//Check if the form has been submitted"

if(isset($_POST['submitted'])) {

 

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

 

//Retrieve the users information:

$q = "SELECT CONCAT(first_name, ' ', last_name) FROM users WHERE user_id=$id";

$r = @mysqli_query ($dbc, $q);

 

if (mysqli_num_rows($r) == 1) { // Valid user ID, show the form

 

// Get the user's information

$row = mysqli_fetch_array($r, MYSQLI_NUM);

 

//Create the form"

echo '<form action="delete_user.php" method="post">

<h3>Name: ' . $row[0] . '</h3>

<p>Are you sure you want to delete this user?<br />

<input type="radio" name="sure" value="Yes" /> Yes

<input type="radio" name="sure" value="No" checked="checked" /> No</p>

<p><input type="submit" name="submit" value="Submit" /></p>

<input type="hidden" name="submitted" value="TRUE" />

<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');

?>

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So,

While I've played with this every which way I have discovered that, the id variable that shows in the url (localhost/sitename/delete_user.php?id=6) disappears from the url when I click the Submit button (localhost/sitename/delete_user.php). Please can you explain where it went, why that does that, and how to prevent that? Thanks

 

M

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The elseif where you check for a $_POST value you then set $id using the $_GET value. This should perhaps use the $_POST if I had to guess. Again I'm on my phone.

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