我会使用 lead():

select min(id) + 1
from (select t.*,
             lead(id) over (order by id) as next_id
      from t
     ) t
where next_id <> id + 1;

如果您想确保 id 从 1 开始(因此如果缺少1"，则返回)，您可以这样做:

If you want to ensure that the ids start at 1 (so if "1" is missing, then return that), you can do:

select (case when min(minid) <> 1 then 1 else min(id) + 1 end)
from (select t.*, min(id) over () as minid
             lead(id) over (order by id) as next_id
      from t
     ) t
where next_id <> id + 1;