Example in Kevin Yank´s book won´t work (involves INNER JOIN and foreach()) page 151

PHP
1

I´m reading Kevin Yank´s book “PHP and MySQL Novice to Ninja 5th edition”, and found an error there in the code, and would like someone to help me out with it, maybe is a silly typo…?

I´m trying to follow the author´s example of creating and accessing a database of jokes. I´m learning how to join two databases to show with php a list of all the jokes. I have two databases joke and author. I´ve got this:

try{
    $sql = 'SELECT joke.id, joketext, jokedate, name, email
    FROM joke INNER JOIN author
    ON authorid = author.id';
    $result = $pdo->query($sql);
}
catch (PDOException $e)
{
    $error = 'Error: ' . $e->getMessage();
    include 'error.html.php';
    exit();
}

foreach ($result as $row)
{
    $jokes[] = array(
    'id' => $row['id'],
    'text' => $row['joketext'],
    'date' => $row['jokedate'],
    'name' => $row['name'],
    'email' => $row['email']
    );
}
include 'jokes.html.php';

Now, all was working ok, until I´ve replaced the simple code to select the database information from just one table, to the INNER JOIN code. This is the book´s code, wich I´ve followed.

In the jokes.html.php file, I´ve got this (wich I think is what´s giving me the error):

   foreach($jokes as $joke):
      <form action="?deletejoke" method="post">
  <?php
      echo 'id. ';
  echo htmlspecialchars($joke['id'], ENT_QUOTES, 'UTF-8');
  echo htmlspecialchars($joke['date'], ENT_QUOTES, 'UTF-8');
  echo htmlspecialchars($joke['text'], ENT_QUOTES, 'UTF-8');
  echo htmlspecialchars($joke['name'], ENT_QUOTES, 'UTF-8');
      echo htmlspecialchars($joke['email'], ENT_QUOTES, 'UTF-8');
  ?>
  <input type="hidden" name="id" value="<?php echo $joke['id'];?>">
  <input type="submit" value="Borrar">
  ?>
  <br></form>
<?php endforeach; ?>

Now, the error that throws me is:

Notice: Undefined variable: jokes in C:\\xampp\\htdocs\\workspace1\\jokes.html.php on line 10

Warning: Invalid argument supplied for foreach() in C:\\xampp\\htdocs\\workspace1\\jokes.html.php on line 10

Line 10 of jokes.html.php is:

foreach($jokes as $joke):

I´m trying to get more information about foreach() but I can´t spot the error… If anyone could help me out a bit (or maybe a clue!) I would be very grateful.
Thanks!!!
Rosamunda

2

UPDATE:

As the result of the query (trying it directely from phpmyadmin) was zero, so there were no database results for that query. I´ve decided to manually add one result doing this:

INSERT INTO joke SET
joketext = ‘this is a new joke…’,
jokedate = ‘2012-01-01’,
authorid = 1;

Now, the errors have dissapear, and that single results does show.

What I don´t understand is:

Why didn´t just no result showed up, instead of those errors?
How do you manage these situations? I mean, it can happen that a query just have no results at all, is it common to result in those errors?

Thanks again for your help!!! Rosamunda

3

It is because of your php settings to show Notices and Warnings. The notice/warning is valid because you were attempting to use the $jokes variable before you declared/assigned a value to it. You can solve this by putting $jokes = array(); before

foreach ($result as $row) 
{ 
    $jokes[] = array( 
    'id' => $row['id'],  
    'text' => $row['joketext'],  
    'date' => $row['jokedate'], 
    'name' => $row['name'], 
    'email' => $row['email'] 
    ); 
}

That will at least declare the $jokes variable for in the event that there are zero results.

4

Oh I see!! THANKS!!!

5

In order to handle the situation where you have no jokes in your database, you would need to set the $jokes variable to contain an empty array before filling it with your database records (which doesn’t happen if there are no database records!). You can do this by adding a statement before the foreach in your index.php:

$jokes = array();

Hope that helps!