Preventing Duplicate entry

[kpowning]

Is there any way to prevent a duplicate entry for a newsletter signup form? Basically I'm looking for this form to query the database and print or echo and error saying " Sorry, that email address is already subscribed!" How can I do this? Please help.

My variable for the email address being collected is: Email_Address and my database is called Newsletter.

I would really, really, appreciate any help here, I'm still trying to learn this php stuff.

[laserlight]

Well, one way would be to attempt to select from the given table using the email address.
If no rows are returned, proceed with inserting a new row.
Otherwise, reject the application.

[kpowning]

Ok, I'm an idiot... How can I do this?

[laserlight]

If you're an idiot you cant do that, sorry :p

Actually, it depends.
What database are you using?
Do you have any code that you are currently working with?