匹配的正则表达式后跟一个或多个单词？

Question

--Return rows that have one or more words that follow a string that
--begins with 'Call me Ishmael.'


with string_row as
( select 'Call me Ishmael.'                as line_1 from dual union all     --False
  select 'Call me Ishmael. Some years ago   .' as line_1 from dual union all --True
  select 'Call me Ishmael  Some years ago   .' as line_1 from dual union all --True
  select 'Call me Ishmael,  Some years ago   .' as line_1 from dual union all --True
  select 'Call me Ishmael .'                 as line_1 from dual union all    --False
  select 'Twas the best of times. Some years ago.' as line_1 from dual union all --False
  select 'Call me Ishmael     '             as line_1 from dual  -- False
)  
select line_1
        from string_row where 
        regexp_like(line_1,'Call me Ishmael\w{1,}')  --original attempt.
        regexp_like(line_1,'Call me Ishmael[., ]+\b([\w .,]+)') --Attempt that appears to work on Javasrcipt.

问题：

为什么这个正则表达式不起作用？

正则表达式的作用是什么？

Answer 1

这个正则表达式有效：

Call me Ishmael[., ]+\b([\w .,]+)

Debuggex Demo

Call me Ishmael 之后的文本和后面的任何句号，逗号或空格都会被放入捕获组1中。

正则表达式的问题，Call me Ishmael\w{1,}

它是否尝试匹配任何字母，数字或下划线（{1,}）中的一个或多个（+，相当于\w）。您的许多行都包含逗号，空格和句点，因此需要对其进行扩展以捕获这些字符。

---

似乎Oracle regex没有字边界。所以试试这个：

Call me Ishmael[., ]+(\w[\w .,]*)

Debuggex Demo