add $wpdb->upsert function
|Reported by:||thomask||Owned by:|
If i read http://codex.wordpress.org/Class_Reference/wpdb right, we have only insert and update functions, but for many occations, if would be lovely, if we would have upsert function as well (using INSERT ... ON DUPLICATE KEY UPDATE http://dev.mysql.com/doc/refman/5.1/en/insert-on-duplicate.html).
So when i am inserting e.g. posts using database function, i do not have to check if post with that id exist (good for some migration / importing tools etc.)