sql删除重复数据

declare   @max   integer , @id   integer
declare  cur_rows  cursor  local  for   select  id, count ( * )  from  表名  group   by  id  having   count ( * )  >   1
open  cur_rows
fetch  cur_rows  into   @id , @max
while   @@fetch_status = 0
begin
     select   @max   =   @max   - 1
     set   rowcount   @max
     delete   from  表名  where  id  =   @id
     fetch  cur_rows  into   @id , @max
end
close  cur_rows
set   rowcount   0