游标（自用的例子）

deallocate cur
declare cur cursor scroll
for select yy from tt
 

open cur

declare @Smallid varchar(50)

fetch  from cur 
 
 --while @@fetch_status=0
 --begin  
  update tt set yy=755 where current of cur      
/*  fetch next from cur 
update tt set yy=55 where current of cur 
 fetch next from cur
update tt set yy=555 where current of cur 
 fetch next from cur
update tt set yy=555555 where current of cur 
 
*/
 --end 

close cur
deallocate cur