Fatal error: Call to a member function setQuery() on a non-object in /home/p0oo9ip0o/public_html/plugins/content/botphp_content.php(53) : eval()'d code on line 4

I saw this fatal error when i use this

<?php $query = "SELECT title FROM #__categories WHERE id = ".intval($article->catid)." LIMIT 1";  
$database->setQuery($query);  
$category = $database->loadResult();
$custom_text = 'this '.$article->title.' belongs to'.$category;
$article->text = str_replace('{additionaltext}', $custom_text, $article->text); ?

You need to retrieve the Database Class Instance to the scope of your code. The event plugins execute in a local scope. (That is, global objects are not available).

$database =& JFactory::getDBO();

Place that before any code where you use $database.