相关疑难解决方法(0)

我的表的结构如下：

@Entity(tableName = "userFitnessDailyRecords")

public class UserFitnessDailyRecords {



    @NonNull
    @PrimaryKey
    private Date forDay;
    private int stepCount;
}

我正在编写的用于获取总和和平均值的查询如下：

@Dao
public interface UserFitnessDailyRecordsDao {


    @Query("SELECT SUM(stepCount), AVG(stepCount) FROM userFitnessDailyRecords where forDay BETWEEN :startDay AND :endDay ORDER BY forDay ASC")
    UserFitnessDailyRecords getUserFitnessSumAndAverageForLastThirtyDays(Date startDay, Date endDay);


    @Query("DELETE FROM userFitnessDailyRecords")
    void deleteUserFitnessDailyRecord();

}

编译后出现错误，因为列不包含求和和平均值字段，因此无法返回值。在这种情况下，一个收益和平均值如何计算？