Question

我正在尝试创建一个显示包含开始和结束时间的事件的视图。应该从仅具有事件时间字段和事件类型字段的现有表中收集此视图。

所以当前的EventTable看起来像这样：

EventTime       | BooleanField
------------------------------
1/1/2010 6:00AM        1
1/2/2010 6:00AM        0
1/3/2010 6:00AM        1
1/4/2010 6:00AM        1
1/5/2010 6:00AM        0

结果集应如下所示

StartTime       | EndTime
-----------------------------
1/1/2010 6:00AM   1/2/2010 6:00AM
1/3/2010 6:00AM   1/5/2010 6:00AM

因此视图应显示布尔字段为true的句点。

在SQL Server 2008中是否有一个简单的解决方案来实现这一目标？

谢谢你的帮助！

Answer 1

您可以尝试类似（完整示例）

DECLARE @EventTable TABLE(
        EventTime DATETIME,
        BooleanField INT
)

INSERT INTO @EventTable (EventTime,BooleanField) SELECT '1/1/2010 6:00AM',1 
INSERT INTO @EventTable (EventTime,BooleanField) SELECT '1/2/2010 6:00AM',0 
INSERT INTO @EventTable (EventTime,BooleanField) SELECT '1/3/2010 6:00AM',1 
INSERT INTO @EventTable (EventTime,BooleanField) SELECT '1/4/2010 6:00AM',1 
INSERT INTO @EventTable (EventTime,BooleanField) SELECT '1/5/2010 6:00AM',0

;WITH Dates AS (
        SELECT  *,
                (SELECT MIN(EventTime) FROM @EventTable WHERE EventTime > e.EventTime AND BooleanField = 0) EndDate
        FROM    @EventTable e
        WHERE   BooleanField = 1
)
SELECT  MIN(EventTime) StartDate,
        EndDate
FROM    Dates
GROUP BY EndDate

Answer 2

试试这个：

SELECT MIN(iq.StartTime), iq.EndTime
FROM 
(
    SELECT e1.EventTime AS StartTime, MIN(e2.EventTime) AS EndTime
    FROM EventTable e1
    LEFT JOIN EventTable e2 ON e2.BooleanField = 0 AND e2.EventTime > e1.EventTime
    WHERE e1.BooleanField = 1
    GROUP BY e1.EventTime 
) iq
GROUP BY iq.EndTime

这将确保您获得每个EndTime的最大间隔。我很确定由于需要两个GROUP BY子句而无法将其简化为单个SELECT查询 - 即使考虑其他示例（通过使用两个不同的聚合函数使用隐式分组，因此等效于此例子）。

Answer 3

怎么样？

  Select s.EventTime StartTime,
         e.EventTime EndTime
  From EventTable s
     Left Join EventTable e 
         On s.BooleanFiels = 1
            And e.BooleanField = 0
            And e.EventTime =
               (Select Min(EventTime) 
                From EventTable 
                Where e.BooleanField = 0
                   And EventTime > s.EventTime)
  Order By s.EventTime

将两个日期时间字段组合到T-SQL中的两个单独的列中

3 个答案: