Mysql SpringData JPA左联接子查询

此SQL在mysql中运行良好，但在SpringData JPA中运行错误，我如何在SpringData JPA中使用它？

您应该尝试强制使用DB引擎以nativeQuery=true运行SQL：

select sm.* 
from   system_mail sm 
left join (SELECT u.mail_code 
           from   user_mail u 
           where u.to_user = 1 ) um 
on sm.mail_id = um.mail_code 
where um.id is null.

@Query(nativeQuery = true, value="...yourqueryhere...")