如果需要完整的行，可以使用：

select t.*
from t
where n < 0
order by n asc
fetch first 1 row only;

如果有另一列指定行的顺序，则：

select t.*
from t
where n < 0
order by <ordering col> asc
fetch first 1 row only;

要选择最大负数，可以执行以下操作：

select max(n)
from t
where n < 0

请记住，在关系数据库表中，行没有固有的顺序。因此，在没有排序标准的情况下，不存在“负值开始的第一行”这样的东西。

假设您有一个用于排序的列，它定义了行的顺序，它可以如下所示：

with t as (
select 77  a, 1  row_order  from dual union all
select 74  a, 2 row_order from dual union all
select 67  a, 3 row_order from dual union all
select 56  a, 4 row_order from dual union all
select 42  a, 5 row_order from dual union all
select 24  a, 6 row_order from dual union all
select 20  a, 7 row_order from dual union all
select 19  a, 8 row_order from dual union all
select -17 a, 9 row_order from dual union all
select -28 a, 10 row_order from dual union all
select -31 a, 11 row_order from dual union all
select -36 a, 12 row_order from dual
), t1 as (
select a, row_number() over (partition by case when a < 0 then 0 else 1 end order by row_order) rn from t
)
select * from t1 where rn = 1 and a < 0;

它使用一个窗口函数来确定第一行（这里是正数a和负数a），然后它选择遇到的第一行是负数。