On duplicate key delete

I cant't find anything on net about that. Surprised that MySQL does not have that build in.

possible usage:

not normalized db, in which case we would not need ON DUPLICATE KEY DELETE:


id val
1 on
2 of
3 null
4 on
....


normalized db

master:

id
1
2
3
4
....



detail:

id
1
3
....

You are correct there is no delete on duplicate in mtsql.

But here's a simple and fast way of doing it:
http://www.justin-cook.com/wp/2006/12/12/remove-duplicate-entries-rows-a-mysql-database-table/