Is it possible to insert a row but only if a value does not already exist?

Question

Is it possible to insert a row, but only if one of the values already in the table does not exist?

I\'m creating a Tell A Friend with referral points for an eco

Answer 1

A slight modification/addition to naeblis's answer:

INSERT INTO table (email) VALUES (email_address)
ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id)

This way you don't have to throw email=email_address in there and you get the correct value for LAST_INSERT_ID() if the statement updates.

Source: MySQL Docs: 12.2.5.3