oracle REGEXP_LIKE()正则表达式问题

这是从oracle官方文档上截下来的

Equivalence Class '[= =]' in Regular Expressions

Oracle Database also supports equivalence classes through the [= =] syntax as recommended by the POSIX standard. A base letter and all of the accented versions of the base constitute an equivalence class. For example, the equivalence class [=a=] matches ä as well as â. The current implementation does not support matching of Unicode composed and decomposed forms for performance reasons. For example, ä (a umlaut) does not match 'a followed by umlaut'.
只翻译关键部分： [=a=] 会匹配 ä 和â等类似的字符