摘自于网路:http://www.cnblogs.com/joinger/articles/1297160.html
update h_crm_SafetyAccessUser set
cancreate=case when a.cancreate=0 then b.cancreate else a.cancreate end,
canedit=case when a.canedit=0 then b.canedit else a.canedit end,
canbrowse=case when a.canbrowse=0 then b.canbrowse else a.canbrowse end,
candelete=case when a.candelete=0 then b.candelete else a.candelete end
from h_crm_SafetyAccessUser a join (select * from h_crm_SafetyAccessUser where clientid=@Targetid) b
on a.modalid=b.modalid and a.Userid=b.Userid
where a.clientid=@clientid
==============================================
declare @t table(x char,y char)
declare @str varchar(20)
select * from @t
set @str='select 4+5'
execute (@str)