insert 表2
select 
a.ID
from 表1 as a,(select top 20 ID from syscolumns) as b
where a.ID=a

------解决方案--------------------
双循环 
SQL code
declare @id varchar(10),@n int=1 ,@i int=1
while exists(select 1 from (select *,ROW_NUMBER() over(order by getdate()) rid from tb)a where rid=@n)
begin
   select @id=id  from  tb where rid=@n
   while @i<=20
   begin
     insert into b select id from a
     set @i = @i + 1
   end
   set @n=@n+1
end

------解决方案--------------------
declare @id
  declare @cursor_Insert cursor for
  select Id from table1
  open @cursor_Insert
  fetch next from @cursor_Insert into @id
  
  while @@FETCH_STATUS=0
  begin
    ..插入20行数据.
     fetch next from @cursor_Insert into @id

  end
  close @cursor_Insert
  deallocate @cursor_Insert

------解决方案--------------------
探讨


抱歉我前面没说清问题，现在补充下
表1为pointhistory表，表结构：id  routehistoryid  pointname  membername
表2为itemhistory表，表结构：id  routehistoryid  pointhistoryid  pointname  itemname  
现在想从表1中取id（即表2的pointhistoryid）生成20条数据插……


------解决方案--------------------
探讨

表1的内容为id routehistoryid pointname membername
  2541 451263252 发电机 李明

现在取id添加到表2中，id routehistoryid pointhistoryid pointname itemname
  12345 451263252 2541 发电机 温度1
  12456 451263252 2541 发电机 温度2
  451256 451263252 2541 发电机 温度3