Question

我有一个基于CTE的查询，我在其中检索两个给定时间跨度之间的每小时间隔。我的查询工作如下：

获取开始和结束日期时间（比如说07-13-2011 00:21:09和07-31-2011 21:11:21）获取每小时间隔之间的每小时总查询值（此处为00到00） 21，总共21个小时，但这是参数，取决于我为每天输入的小时数。

此查询适用于第一个时间戳的小时小于第二个时间的输入-e.g.上午03点是第一个时间戳的小时，上午07点是第二个时间戳的小时，但是有一个问题。当我想检索输入的总计数时，例如07-13-2011 22:11:43和07-25-2011 04:06:04，我遇到了问题。我需要检索以下查询的总计数：

07-13-2011 22:00:00    143 //representing the total amounts of queries 22:11:43 - 22:59:59 interval-
07-13-2011 23:00:00    121 //representing the total amounts of queries in 23:00:00  -23:59:59 interval-
07-14-2011 00:00:00     65 //00:00:00  - 00:59:59 interval
07-14-2011 01:00:00     51 //01:00:00  - 01:59:59 interval...
.
.
.
07-14-2011 04:00:00  22  //query amount for 04:00:00 - 04:06:04 interval

等等。除了我在下面写的CTE查询之外，我还需要做什么？

WITH cal AS (
    SELECT generate_series('2011-02-02 00:00:00'::timestamp
                         , '2012-04-01 05:00:00'::timestamp
                         , '1 hour'::interval) AS stamp
    )
, qqq AS (
    SELECT date_trunc('hour', calltime) AS stamp
    , count(*) AS zcount
    FROM mytable
    WHERE calltime >= '07-13-2011 22:00:00'
    AND calltime <='07-31-2011 04:33:21' 
    AND calltime::time >= '22:00:00' 
    AND calltime::time <= '04:33:21'
    -- this calltime::time part obviously doesn't work due to common sense and logic
    -- edited it to show what I try to mean 
    AND date_part('hour', calltime) >= 0
    AND date_part('hour', calltime) <= 21
    GROUP BY date_trunc('hour', calltime)
    )
SELECT cal.stamp
     , COALESCE (qqq.zcount, 0) AS zcount
FROM cal
LEFT JOIN qqq ON cal.stamp = qqq.stamp
WHERE cal.stamp >= '07-13-2011 22:00:00'
AND cal.stamp<='07-31-2011 04:33:21'
AND date_part('hour', cal.stamp) >= 0
AND date_part('hour', cal.stamp) <= 21
ORDER BY stamp ASC;

Answer 1

考虑这个修正版本：

WITH param AS (
   SELECT '2011-07-13 22:11:43'::timestamp AS start -- supply start / stop once
         ,'2011-07-25 04:06:04'::timestamp AS stop
   )
   , cal   AS (
   SELECT generate_series(date_trunc('hour', p.start)
                         ,date_trunc('hour', p.stop + interval '1h')
                         ,interval '1h') AS h
   FROM param p
   )
   , q    AS (
   SELECT date_trunc('hour', calltime) AS h
         ,count(*) AS ct
   FROM   mytable
         ,param p
   WHERE  calltime >= p.start
   AND    calltime <= p.stop
   -- uncomment if you actually want to exclude hours 22 & 23 (?)
   -- AND    extract('hour' FROM calltime) BETWEEN 0 AND 21
   GROUP  BY 1
   )
SELECT cal.h, COALESCE(q.ct, 0) AS ct
FROM   cal
LEFT   JOIN q USING (h)
-- uncomment if you actually want to exclude hours 22 & 23 (?)
-- WHERE  extract('hour' FROM cal.h) BETWEEN 0 AND 21
ORDER  BY 1;

主要变化是立即从实际时间跨度中产生小时数删除了一些不必要的条件使用ISO 8601格式表示时间戳（适用于所有语言环境）。

在此related answer查找更多上下文和链接。唯一的区别是：在那里它是关于运行计数。

Answer 2

本条：

AND calltime::time >= '00:21:09' AND calltime::time <= '21:11:21'

鉴于其他条款，

看起来很可疑。

目前尚不清楚为什么需要它，如果分别以22:11:43和04:06:04作为示例给出的字面时间不起作用，则此子句将过滤掉所有内容，以便您结束每小时最多0个计数。

当时间戳的开始时间大于时间戳的结束时间时，查询失败

2 个答案: