sql 游标的使用

一个例子：从tszl表中查出数据，根据cs字段的值决定往BOOK_SERIAL表中插入几行数据。
declare @num int
declare @id varchar(60)
declare @classbm varchar(60)
set @classBm='101'
declare id cursor for select id,cs from  [tszl]
open id
fetch next from id into @id,@num
while @@fetch_status!=-1
 begin
    while(@num>0)
      begin
  set @num = @num-1
 INSERT INTO  [BOOK_SERIAL]
           ([id]
           ,[classBm]
           ,[state])
  values(@id,@classBm,'0')
      end
fetch next from id into @id,@num
   end
close id