I've got a table that may contain rows with duplicates value in one of the columns. If duplicates exist in that column, I want to delete the duplicates, leaving only one. Is there a one statement sql query for doing that? Note that the timestamp and id will be different between duplicates. Only the order_number will be a duplicate.

table:
email_queue

fields:
id (key)
order_number (may be duplicate)
timestamp