SQL update join on 连接更新

http://stackoverflow.com/questions/1293330/how-can-i-do-an-update-statement-with-join-in-sql
create table sale
(
id int,
udid int,
assid int
)

create table ud
(
id  int,
assid  int
)

select * from sale
select * from ud

select * 
from sale inner join ud on sale.id = ud.id

update sale set sale.assid = ud.assid
from sale inner join ud on sale.id = ud.id