按ASC和DESC排序

Question

我有一个spa表，其中包含我需要的大多数信息：

然后我加入另一个表client，以获取last_name字段：

我需要为每个room_code和service_detail获得第一个provider_start_time，sba_date和provider_code，以及最后一个< / strong> provider_end_time。

以我的图片为例，预期结果将是：

Answer 1

我认为可以使用窗口函数row_number()和last_value()来做到这一点：

select
    room_code,
    service_detail,
    sba_date,
    provider_start_time,
    provider_end_time,
    last_name
from (
    select 
        s.*,
        c.last_name,
        row_number() over(
            partition by s.sba_date, s.provider_code
            order by s.provider_start_time
        ) rn,
        last_value(provider_end_time) over(
            partition by s.sba_date, s.provider_code
            order by s.provider_start_time
            range between unbounded preceding and unbounded following
        ) provider_end_time
    from spa s
    inner join client c on c.client_code = s.provider_code
) t
where rn = 1

内部查询将两个表连接起来，并通过将sba_date递增来对具有相同provider_code和provider_start_time的记录组中的记录进行排名；它还计算同一组中provider_end_time的最后一个值。然后，外部查询将对每个组中的第一条记录进行过滤。

Answer 2

您还可以使用某些CTE或子查询：

;WITH cte AS ( --getting min and max time for particular provider on some date
SELECT sba_date,
       MIN(provider_start_time) as provider_start_time,
       MAX(provider_end_time) as provider_end_time,
       provider_code
FROM spa
GROUP BY sba_date, provider_code
)
-- here goes join to clients (last_name) and original table to get room and detail
SELECT s.room_code,
       s.service_detail,
       c.sba_date,
       c.provider_start_time,
       c.provider_end_time,
       cl.last_name
FROM cte c
INNER JOIN client cl
   ON c.provider_code = cl.client_code
INNER JOIN spa s
   ON s.sba_date = c.sba_date0
    AND s.provider_code = c.provider_code
    AND s.provider_start_time = c.provider_start_time