sql update set使用case when语句

1、

update TD_XXX
set
djyzmdm=null,
djyzmsj=null,
DLCS= case when DLCS is null then 1 else DLCS+1 end
where djsj='xxx'

2、
update `TD_XXX`
set
`datetime` = 1434567890,
`status` = case `id` when 12 Then 1 when 13 Then 2 when 14 Then 1 end
where `id` in (12,13,14)