SQL - 向 SELECT 添加条件

Question

我有一个表，其中包含机器的时间戳和 inCycle 状态。我正在使用两个 CTE 并在行号上执行 INNER JOIN，因此我可以轻松地将一行的时间戳与下一行的时间戳进行比较。我有 DATEDIFF 工作，现在我需要查看 inCycle 状态。基本上，如果 inCycleThis 和 inCycleNext 都 = 1，我需要将它添加到 InCycle 总数中。

类似地（显示的表格会说明这一点）：

incycleThis/next = 0,1 = not in cycle
incycleThis/next = 0,0 = not in cycle
incycleThis/next = 1,1 = in cycle

如果我在做这个客户端，这将非常简单。由于有很多记录，我需要在存储过程中执行此操作。我很想在 SELECT 部分使用“IF”，但它似乎不是这样。

我在最后寻找的结果很简单：InCycle = Xtime。比如：

SUM(Diff_seconds if((InCycleThis = 1 AND InCycleNext = 1) OR (InCycleThis = 1 AND InCycleNext = 0))

这是我目前所拥有的：

WITH History_CTE (DT, MID, FRO, IC, RowNum)
AS
(
SELECT DateAndTime
    ,MachineID
    ,FeedRateOverride
    ,InCycle
    ,ROW_NUMBER()OVER(ORDER BY MachineID, DateAndTime) AS "row number"
FROM History
WHERE DateAndTime >= '2020-11-15'
    AND DateAndTime < '2020-11-16'
),

History2_CTE (DT2, MID2, FRO2, IC2, RowNum2)
AS
(
SELECT DateAndTime
    ,MachineID
    ,FeedRateOverride
    ,InCycle
    ,ROW_NUMBER()OVER(ORDER BY MachineID, DateAndTime) AS "row number"
FROM History
WHERE DateAndTime >= '2020-11-15'
    AND DateAndTime < '2020-11-16'
)
SELECT DT as 'TimeStamp'
,DT2 as 'TimeStamp Next Row'
,MID
,FRO
,IC as 'InCycle this'
,IC2 as 'InCycle next'
,RowNum
,DATEDIFF(s, History2_CTE.DT2, History_CTE.DT) AS 'Diff_seconds'
FROM History_CTE
INNER JOIN
    History2_CTE ON History_CTE.RowNum = History2_CTE.RowNum2 + 1

Answer 1

考虑添加第三个 CTE 以首先有条件地计算您需要的值。然后聚合为最终语句。召回 CTE 可以引用先前定义的 CTE。确保始终在 JOIN 查询中使用表别名来限定列。

WITH 
    ... first two ctes...
, sub AS (
  SELECT  h1.DT AS 'TimeStamp'
        , h2.DT2 AS 'TimeStamp Next Row'
        , h1.MID
        , h1.FRO
        , h1.IC AS 'InCycle this'
        , h2.IC2 AS 'InCycle next'
        , h1.RowNum
        , DATEDIFF(s, h2.DT2, h1.DT) AS 'Diff_seconds'
        , CASE 
             WHEN (h1.IC = 1 AND h2.IC2 = 1) OR (h1.IC= 1 AND h2.IC2 = 0)
             THEN DATEDIFF(s, h2.DT2, h1.DT) 
          END AS 'IC_Diff_seconds'
  FROM History_CTE h1
  INNER JOIN History2_CTE h2
     ON h1.RowNum = h2.RowNum2 + 1
)

SELECT SUM([Diff_seconds]) AS Diff_seconds_Total
     , SUM([IC_Diff_seconds]) AS IC_Diff_seconds_Total
FROM sub

如果需要添加分组，请合并GROUP BY：

SELECT h1.MID
     , h1.FRO
     , SUM([Diff_seconds]) AS Diff_seconds_Total
     , SUM([IC_Diff_seconds]) AS IC_Diff_seconds_Total
FROM sub
GROUP BY h1.MID
       , h1.FRO

甚至按天汇总计算：

SELECT CONVERT(date, [TimeStamp]) AS [Day]
     , SUM([Diff_seconds]) AS Diff_seconds_Total
     , SUM([IC_Diff_seconds]) AS IC_Diff_seconds_Total
FROM sub
GROUP BY CONVERT(date, [TimeStamp])

Answer 2

我在最后寻找的结果很简单：InCycle = Xtime。比如：

SUM(Diff_seconds if((InCycleThis = 1 AND InCycleNext = 1) OR (InCycleThis = 1 AND InCycleNext = 0))

据我了解您的问题，您只需将“循环中”行的时间戳与下一行的时间戳之间的差相加即可。

select machineid, 
    sum(datediff(s, dateandtime, lead_dateandtime)) as total_in_time
from (
    select h.*, 
        lead(dateandtime) over(partition by machineid order by dateandtime) as lead_dateandtime
    from history h
) h
where inclycle = 1
group by machineid