值到先前行的比較依賴於不同的領域

Question

我有SQL其中輸出日期時間標記和狀態改變標誌的行（0或1）

我需要從第一條記錄獲取時間跨度，標誌將爲0，狀態標誌變爲1時，忽略標誌爲1時的記錄，然後在變回0直到最後一條記錄後獲得時間跨度。狀態改變標誌可以在0和1之間任意次數翻轉。

所以我需要能夠比較狀態更改標誌與前一行，並決定是否需要不斷累積日期時間戳的差異。

我一直在尋找寫一個遊標，但不斷閱讀遊標是如何非常低效。

希望這是有道理的。

Answer 1

DECLARE @test TABLE ([group] int,t DateTime,[status] bit) 

INSERT INTO @test values (1,'20130101 11:11:11',0) 
INSERT INTO @test values (1,'20130101 11:11:12',0) 
INSERT INTO @test values (1,'20130101 11:11:13',0) 
INSERT INTO @test values (1,'20130101 11:11:14',1) 
INSERT INTO @test values (1,'20130101 11:11:15',1) 
INSERT INTO @test values (1,'20130101 11:11:16',1) 
INSERT INTO @test values (1,'20130101 11:11:17',0) 
INSERT INTO @test values (1,'20130101 11:11:18',0) 
INSERT INTO @test values (1,'20130101 11:11:19',0) 


Select [Group],MIN(t) 

,(Select MAX(t) from @test t2 where [status]=0 and t2.[group]=t.[group] and Exists(Select * from @test t3 where [status]=1 and t3.[group]=t.[group] and t3.t<t2.t)) 
,DateDiff(ss,MIN(t) 
,(Select MAX(t) from @test t2 where [status]=0 and t2.[group]=t.[group] and Exists(Select * from @test t3 where [status]=1 and t3.[group]=t.[group] and t3.t<t2.t)) 
) as Seconds 
from @test t where Status=0 
group by [group] 

Answer 2

我覺得這樣的事情會起作用。但我可能需要關於表結構的更多信息

WITH FirstFlag(FlagType, FlagTime) 
AS 
(
    SELECT 
     FlagType 
     , min(DateCreated) as FlagTime 
    FROM TheTable 
    WHERE Flag = 0 
) 
, SecondFlag(FlagTime1, FlagTime2) 
AS 
(
    SELECT 
     F.FlagTime as FlagTime 
     , min(T.DateCreated) as FlagTime 
    FROM TheTable as T 
     INNER JOIN FirstFlag as F 
      ON T.FlagType = F.FlagType 
    WHERE Flag = 1 
     AND T.DateCreated > F.FlagTime 
) 
SELECT datediff(min, FlagTime1, FlagTime2) 
FROM SecondFlag