查询避免Unknown column ‘xxx’ in ‘where clause’

在使用jpa的操作时候出现了这样的异常

 Unknown column '‘Y’' in 'where clause'

sql代码是这样的：

    @Query(value = "SELECT * FROM eval_qn_option qq WHERE  qq.validate_flag='Y' and qq.question_id=?1", nativeQuery = true)
    List<EvalQnOption> findByquestionId(String questionId);

后来改啊改：

Constant.VALIDATEFLAG_Y 接口常量

    @Query(value = "SELECT * FROM eval_qn_option qq WHERE  qq.validate_flag='"+ Constant.VALIDATEFLAG_Y +"' and qq.question_id=?1", nativeQuery = true)
    List<EvalQnOption> findByquestionId(String questionId);