SQL服務器 - 選擇最新記錄產生變化

Question

下面的列表的情況是：

我的「票」一個數據庫，我們跟蹤每個它們保存時間更改門票。我專門找在狀態發生變化，這與以下格式跟蹤：

狀態：{FROM}：{TO}

與{FROM}和{TO}更改爲相應的狀態。我需要做的是在任何給定的一週結束時，例如在過去的12周內，按照「開放」（意味着處於草稿狀態）的票數週數來生成數字。但是，您並不僅限於「關閉」票證，然後重新打開它，或者在一週內進行多次更改。

所以，我需要做的是修改下面的SQL，只考慮任何給定條目的最新「動作」。這樣我們就避免了由於已經打開計數而出現「已關閉」的條目，因爲它們已經提前打開。

SELECT track.historyID 
     FROM RS_HistoryTracker track 
    WHERE (track.action = 'STATUS:INITIAL:DRAFT' 
      OR track.action = 'STATUS:DELETED:DRAFT' 
      OR track.action = 'STATUS:DRAFT:DRAFT') 
     AND track.trackDateTime <= @endOfWeek 

不過，這一說法被包含在另一個SELECT語句中，並且被用來產生的歷史項目的完整列表：

SELECT COUNT(DISTINCT his.historyID) AS theCount 
    FROM RS_History his 
WHERE his.historyID IN 
     (SELECT track.historyID 
      FROM RS_HistoryTracker track 
     WHERE (track.action = 'STATUS:INITIAL:DRAFT' 
       OR track.action = 'STATUS:DELETED:DRAFT' 
       OR track.action = 'STATUS:DRAFT:DRAFT') 
      AND track.trackDateTime <= @endOfWeek) 

那麼，如何使只有內部的選擇考慮到最近追蹤到達或在endOfWeek日期的'行動'？ HistoryTracker包含日期時間戳記列。

Answer 1

看起來是這樣工作的：

SELECT query.historyID 
    FROM 
    (SELECT MAX(track.trackID) AS maxTrackID, track.historyID 
    FROM RS_HistoryTracker track 
    WHERE track.trackDateTime <= '2009-08-06 23:59:59' 
     AND track.action LIKE 'STATUS:%' 
    GROUP BY historyID) AS query, RS_HistoryTracker track 
    WHERE track.historyID = query.historyID 
     AND track.trackID = query.maxTrackID 
     AND track.action LIKE 'STATUS:%:DRAFT' 

Answer 2

擔任首發，你可以做這樣的事情

select * from 
(
    --find max history id for each ticket 
    select 
     T1.ticketId, 
     max(T1.historyId) As LastHistoryId 
    from #Ticket T1 
    --add WHERE clause to filter out dates 
    group by 
     T1.ticketId 
) MaxTicket 

inner join 
#Ticket T2 --find the ticket so you can get the status 
on MaxTicket.ticketId = T2.ticketId 
and MaxTicket.LastHistoryId=T2.Historyid 

您可能希望找到每張門票的最後一個歷史記錄項改變你如何找到最新的門票是基於日期，而不是歷史ID。

Answer 3

的是這個問題的漂浮計算器上的很多變化，這裏是我第一次發現:)

sql-query-to-get-most-recent-row-for-each-instance-of-a-given-key

基本上你需要做兩個部分。
- 使用一個查詢發現每件
最近的時間戳 - 使用另一個查詢到你所要做

找到的所有項目仍然由給定日期開放工作：

SELECT 
    [data].* 
FROM 
    track AS [data] 
WHERE 
    [data].trackDateTime = 
    (
     SELECT 
      MAX(trackDateTime) 
     FROM 
      track 
     WHERE 
      track.ticketID = [data].ticketID 
      AND track.DateTime < @endOfWeek 
    ) 
    AND track.action IN ('STATUS:INITIAL:DRAFT','STATUS:DELETED:DRAFT','STATUS:DRAFT:DRAFT')) 

這假定ticketID是每張票的唯一標識符。 （根據您的意見之一）

Answer 4

將與SQL Server 2005+工作：

WITH history AS (
    SELECT rh.historyID, 
     MAX(rh.action) 'action' 
    FROM RS_HISTORYTRACKER rh 
    WHERE rh.action IN ('STATUS:INITIAL:DRAFT', 'STATUS:DELETED:DRAFT', 'STATUS:DRAFT:DRAFT') 
    AND rh.trackDateTime <= @endOfWeek) 
SELECT COUNT(DISTINCT t.historyID) AS theCount 
    FROM RS_HISTORY t 
    JOIN history h ON h.historyi = t.historyid 

備用，非CTE使用查詢：

SELECT COUNT(DISTINCT t.historyID) AS theCount 
    FROM RS_HISTORY t 
    JOIN (SELECT rh.historyID, 
       MAX(rh.action) 'action' 
      FROM RS_HISTORYTRACKER rh 
     WHERE rh.action IN ('STATUS:INITIAL:DRAFT', 'STATUS:DELETED:DRAFT', 'STATUS:DRAFT:DRAFT') 
      AND rh.trackDateTime <= @endOfWeek) h ON h.historyi = t.historyid