如何更改此正则表达式以获得所需的输出？

Question

这是Fiddle。

所需输出

Buy flood insurance. Act now.
Buy flood insurance. Call now.
Buy flood insurance. No change.

这是我的尝试：

    with data_row as (
    select 'or buy flood insurance. Act now.' as disclaimer from dual union  all
    select 'or Buy flood insurance. Call now.' as disclaimer from dual union  all
    select  'Buy flood insurance. No change.' as disclaimer from dual )
    select case        
        when  regexp_like(disclaimer,'^or (B|b)uy flood insurance.*') then 
              regexp_replace(disclaimer,'^or (B|b)uy flood insurance.*','Buy flood insurance.')      
       else disclaimer
       end as revised
 from data_row

Answer 1

只需使用like与lower()一起查找需要更改的内容，并在需要时使用硬编码大写覆盖B：

select 
   case 
     when lower(message) not like 'or b%' then message
     else 'B' || substr(message, 5)
   end message
from disclaimer

请参阅SQLFiddle