create table #t(id int);
insert #t 
select 1
union
select 2
union
select 3
union
select 4
union
select 5
union
select 7
union
select 8



select t1.id-1 as id from 
(select id,row_number() over (order by id ) as num from #t)t1,
(select id,row_numbe() over (order by id )+1 as num from #t)t2
where t1.num=t2.num and t1.id-t2.id>1

drop table #t

------解决方案--------------------
select a.l_id
 from (select rownum l_id from dual connect by rownum <= 10000) a
  where a.l_id not in (select id from a)
刚才把表名写错了，我觉得这样可以实现了，期待更好的办法。

------解决方案--------------------
select b.l_id
 from (select rownum l_id from all_objects where rownum <= (select 10000 + min(id) from a)) b
  where b.l_id not in (select id from a);
用聚合函数取出最小的就可以了

------解决方案--------------------
探讨

我面试遇到这样一个题目：

数据库 表A id为自增
有1W条数据 
其中有一条数据被删除了
现在希望能用一条SQL 查询出被删除的ID