Email already sent?

Can someone explain a simple solution using MySQL and PHP how to check if an email has been sent already, stopping duplicates for users.

I have a basic script, but it's not working for some re开发者_Go百科ason - http://pastebin.com/k7yiQahb It inserts into the table the following:

feed_id, recipient_id, issent

0, 0, Y

Regards

Why not create a column issent of type enum(Yes,No) DEFAULT 'No' in the table recipients instead of a separate table.

Then, when email is sent successfully, run this:

 update `recipients` set issent = 'Yes' where id = $id

And when you are fetching email recipients in the beginning, just do:

 select email, suburb, id FROM recipients where issent = 'No' GROUP BY id ORDER BY id DESC

This will give you only unsent addresses.

[EDIT]: If there are multiple recipients, you can run first query like this:

 update `recipients` set issent = 'Yes' where id IN (3,4,5,6)