How to prevent duplicate posts in my guestbook?

[someone]

I have a little form that people can post their messages, but there has been a lot of duplicate entries by people pressing the submit button twice or by hitting refresh. How do I prevent multiple posts of the same entry?

[kamakaze]

I believe you should be able to set one of the fields to UNIQUE which should stop the duplicate entries.

[jatar_k]

you could generate a key/id when the form is served and is passed in a hidden field. you can check the db for that key everytime someone submits your form, if it exists, no insert.