SpringDataJPA之@Query with LIKE(JPA模糊查询)

对于JPA来说，like查询是不友好的，，例如这么查，是查不出来东西的

@Query("select u from user u where u.username like '%username%'")
List<User> findUserByUsernameLike(@Param("username") String username);

@Query("select u from user u where u.username like '%?1%'")
List<User> findUserByUsernameLike(String username);

=。=这个时候可以用CONCAT函数来帮忙，用column like CONCAT(‘%’,?1,’%’) 进行拼接。如下

@Query("SELECT u.username FROM User u WHERE u.username LIKE CONCAT('%',:username,'%')")
List<String> findUsersWithPartOfName(@Param("username") String username);

核心就是mysql的concat函数，CONCAT（）函数用于将多个字符串连接成一个字符串，是最重要的mysql函数之一

 CONCAT('%',?1,'%') 

再这里感谢stackoverflow大神的回答与启示
https://stackoverflow.com/questions/21456494/spring-jpa-query-with-like

最后，放出一段实战@Query查询

(e.event_title like CONCAT(‘%’,?1,’%’) or ?1 is null)
代表不存在则不查询，存在则进行模糊查询

@Query(value = " select * from event e "
            + " where (e.event_title like CONCAT('%',?1,'%')  or ?1 is null) "
            + " and (to_days(e.register_time)=to_days(?2) or ?2 is null) "
            + " and e.status = '1' "
            + " order by e.register_time desc limit ?3,?4 ",nativeQuery = true)
    List<Event> findAllList(String eventTitle,Timestamp registerTime,Integer pageNumber,Integer pageSize);