在数据不是完整序列时使用Oracle序列

你只想计算最后的值吗 b ?

select pkey, val,
       (case when val like '%b'
             then row_number() over (partition by (case when val like '%b' then 1 else 0 end) order by pkey
                                    )
        end) as b_seq
from table;

如果要查找与特定行相对应的行,可以将其用作子查询 b_seq

如果您不关心其他值,那么使用 where

select pkey, val,
       row_number() over (order by pkey) as b_seq
from table
where val like '%b';

基于戈登的回答,我会:

with
x as (
  select seq.nextval as s
),
y as (
  select pkey, val,
       row_number() over (order by pkey) as b_seq
  from table
  where val like '%b'
)
select y.* from y join x on y.b_seq = x.s