[PHP] Guestbook

[Mr Happy]

Your entering raw data directly into the database. That's very dangerous and the script is prone to attack. You want to do checks on the data before inserting it like mysql_real_escape_string so it will be like:

$name = mysql_real_escape_string($_POST['name']);
$email = mysql_real_escape_string($_POST['email']);
$comment = mysql_real_escape_string($_POST['comment']); 

The other problem is you don't really do checks to see if all the data was entered or entered correctly. eg if someone enters the name and email and then clicks submit before they enter the comment it will still be entered into the database. You should try and add an error message saying please complete all fields.

Otherwise nice job.

EDIT: while I'm at it. If it's a fairly busy site then say 100 people enter comments (which is totally possible) then you'll have 100 comments after another. This isn't great as it's going to be a really long page and not very efficent on the server. Consider adding a LIMIT to the display and maybe add a basic page navigation if it's needed. I'd also suggest using ORDER BY and display the comments in order of date with say the more recent first. You don't want to be reading comments that are a few months old and a comment from yesterday a few pages back.

If you need help with any of the above just ask.