當時間戳的開始時間大於時間戳的結束時間時查詢失敗

Question

我有一個基於CTE的查詢，其中我檢索兩個給定時間間隔之間的小時間隔。我的查詢工作如下：

獲取開始和結束日期時間（比如說07-13-2011 00:21:09和07-31-2011 21:11:21）獲得每小時間隔的小時總查詢值（在這裏是00到21，總共21小時，但這是參數化的，取決於我爲輸入提供的時間）。

此查詢適用於第一個時間戳的小時小於第二個時間的輸入 - 例如， 03 AM是第一個時間戳的時間，07 AM是第二個時間戳的時間，但是存在問題。當我想要檢索輸入的總計數時，如07-13-2011 22:11:43和07-25-2011 04:06:04，我遇到了問題。我需要檢索以下查詢的總計數：

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。除了我在下面寫的CTE查詢外，還需要做些什麼？

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

考慮這個修正版：

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; 

主要的變化是從生成的實際時間跨度小時的時候了。
刪除了一些不需要的條件。
對時間戳使用ISO 8601格式（適用於每種語言環境）。

查找更多的上下文和鏈接在這個related answer。唯一的區別是：在那裏它的運行計數。

Answer 2

這一條款：

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

看起來可疑，考慮到其他條款。

目前尚不清楚爲什麼需要它，並且如果文字時間分別爲22:11:43和04:06:04作爲示例不起作用，則該條款將過濾掉所有內容，以便每小時結束0次計數。