从电子邮件地址学说中获得域名？

Question

对于从电子邮件地址获取域（如sql）有很好的答案。但是无法将其转换为学说语言。

以下查询在mysql中有效。

SELECT (SUBSTRING_INDEX(SUBSTR(email, INSTR(email, '@') + 1),'.',1)) as domain,
       COUNT(*) as C
FROM newsletter_recipient
where LENGTH(email) > 0
GROUP BY (SUBSTRING_INDEX(SUBSTR(email, INSTR(email, '@') + 1),'.',1))
ORDER BY COUNT(*) DESC;

任何人都可以使用querybuilder学说来帮助从电子邮件地址中获取域