Question

我想获得每月的新用户数。应该以该月第一天的0：00h的UTC时间戳（以毫秒为单位，Long表示一个月）。

这种方法可以解释我想做什么：

实体

class User {
    @NotNull
    private Long createdAt; // utc timestamp in ms
}

存储库

public interface UserRepository extends CrudRepository<User, Long> {
    @Query("SELECT new UserRepository$NewUser(to_start_of_month_in_ms(user.createdAt), count(user.id)) "
        + "FROM User user "
        + "GROUP BY to_start_of_month_in_ms(user.createdAt) ")
    List<NewUser> findNewUsersPerMonth();

    @Getter
    @AllArgsConstructor
    public static class NewUser {
        private Long startOfMonth; // utc timestamp in ms
        private Integer count;
    }
}

to_start_of_month_in_ms有什么用，即如何从group by子句的createdAt字段中得出月初。该怎么办 @Query看起来像什么？

Answer 1

我认为在JPQL中是不可能的，因为它不支持日期截断等。对于PSQL使用本机查询，我想到了这一点：

public interface CountPerMonth {
    Integer getCount(); // count within the month
    Long getStartOfMonth(); // timestamp in ms
}

@Query(nativeQuery = true, value = ""
    + "SELECT COUNT(u.id) AS count, "
    + "  DATE_PART('EPOCH', DATE_TRUNC('MONTH',TO_TIMESTAMP(u.created_at/1000) AT TIME ZONE 'UTC'))*1000 AS startOfMonth "
    + "FROM user u "
    + "GROUP BY DATE_TRUNC('MONTH',TO_TIMESTAMP(u.created_at/1000) AT TIME ZONE 'UTC') "
    + "ORDER BY startOfMonth ")
List<CountPerMonth> findNewUsersPerMonth();

jpql：按毫秒分组

1 个答案: