When I tried to run this, PHP treated the word -include- as a control structure rather than an index name. Understandable. So, I put it in single quotes ('include') to see what would happen and it works fine. But I don't understand why!
What is the difference between $content_row [include] and $content_row['include']? I have been unable to resolve this question in the php manual, I need enlightenment.
Without quotes it could be constant or defined variable:
define('variable', 'blah blah blah');
so then I can just use:
<?php
define('variable', 'blah blah blah');
echo variable;
?>
will print out:
blah blah blah
So in your case, it's checking for a defined variable called 'include' which doesn't exist (and prints out a warning/notice).