Question

使用SQL Server 2005

离开表

ID StartDate EndDate 

001 02/03/2010 02/03/2010
002 02/03/2010 null
…

活动表

ID Date 

001 02/03/2010 
001 02/04/2010 
001 02/05/2010 
002 02/03/2010 
002 02/04/2010 
002 02/05/2010 
….

所有日期列数据类型均为datetime。

我有n个id。

我想创建一个状态列，将事件表中的日期与离开表中的结束日期进行比较。

条件1

如果特定ID的休假表中有“开始日期”和“结束日期”，则它应在特定日期的事件表中显示为“离开”

查询

Select 
    id, date
    , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
from event table as t1 
left outer join leave table as t2 on 
    t1.id = t2.id and t1.date between t2.startdate and t2.enddate

条件2

如果开始日期可用且结束日期在特定ID的休假表中不可用，则它应在事件表中显示为“离开”剩余日期

查询

 Select 
        id, date, 
        , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
    from event table as t1 
    left outer join leave table as t2 on 
        t1.id = t2.id and t1.date > t2.startdate

预期产出

ID Date Status

001 02/03/2010  Leave
001 02/04/2010  
001 02/05/2010 
002 02/03/2010 Leave
002 02/04/2010 Leave
002 02/05/2010 Leave
….

以上查询正在运行，但我想使用两个条件进行单个查询

如何查询上述情况。

需要查询帮助

Answer 1

也许这对你有用：

    Select 
    id, date
    , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
from event table as t1 
left outer join leave table as t2 on 
    t1.id = t2.id 
where (t1.date between t2.startdate and t2.enddate)
or (t2.enddate is null and (t1.date > t2.startdate))

Answer 2

试试这个。如果您将来使用假结束日期，则它基本上是相同的查询。

我选择06年6月6日作为最高的smalldatetime值，但您可以根据需要更改

Select 
    id, date
    , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
from
   eventtable as t1 
   left outer join
   leave table as t2 on t1.id = t2.id and
          t1.date between t2.startdate and ISNULL(t2.enddate, '20790606')

Answer 3

我认为在日期中使用'或'条件会成为性能问题（索引使用等）。

也许工会（或工会全部）会更好地运作：

Select 
    id, date
    , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
from event table as t1 
left outer join leave table as t2 on 
    t1.id = t2.id and t1.date between t2.startdate and t2.enddate

Union

Select 
        id, date, 
        , CASE WHEN t2.id IS NULL THEN null ELSE ‘Leave’ END AS status 
    from event table as t1 
    left outer join leave table as t2 on 
        t1.id = t2.id and t1.date > t2.startdate

单个查询有两个条件

3 个答案: