首先,我基于Dave Markle描述的递归公共表查询创建了一个表函数(感谢Dave向我展示这个)。这非常方便,因为我只需要创建一次函数,就可以用它来分析任何区间。
if exists (select * from dbo.sysobjects where name = 'fn_daterange') drop function fn_daterange;
go
create function fn_daterange
(
@MinDate as datetime,
@MaxDate as datetime,
@intval as datetime
)
returns table
as
return
WITH times (startdate, enddate, intervl) AS
(
SELECT @MinDate as startdate, @MinDate + @intval - .0000001 as enddate, @intval as intervl
UNION ALL
SELECT startdate + intervl as startdate, enddate + intervl as enddate, intervl as intervl
FROM times
WHERE startdate + intervl <= @MaxDate
)
select startdate, enddate from times;
go
如果你仅从该函数中进行选择,你将得到一个时间间隔表格,如下所示:
fn_daterange('12/14/2008 10:00:00', '12/14/2008 20:00:00', '01:00:00' )
返回结果如下:
startdate enddate intervl
----------------------- ----------------------- -----------------------
2008-12-14 10:00:00.000 2008-12-14 10:59:59.997 1900-01-01 01:00:00.000
2008-12-14 11:00:00.000 2008-12-14 11:59:59.997 1900-01-01 01:00:00.000
2008-12-14 12:00:00.000 2008-12-14 12:59:59.997 1900-01-01 01:00:00.000
2008-12-14 13:00:00.000 2008-12-14 13:59:59.997 1900-01-01 01:00:00.000
2008-12-14 14:00:00.000 2008-12-14 14:59:59.997 1900-01-01 01:00:00.000
2008-12-14 15:00:00.000 2008-12-14 15:59:59.997 1900-01-01 01:00:00.000
2008-12-14 16:00:00.000 2008-12-14 16:59:59.997 1900-01-01 01:00:00.000
2008-12-14 17:00:00.000 2008-12-14 17:59:59.997 1900-01-01 01:00:00.000
2008-12-14 18:00:00.000 2008-12-14 18:59:59.997 1900-01-01 01:00:00.000
2008-12-14 19:00:00.000 2008-12-14 19:59:59.997 1900-01-01 01:00:00.000
2008-12-14 20:00:00.000 2008-12-14 20:59:59.997 1900-01-01 01:00:00.000
然后我制作了一个事件数据的样本表:
eventdate eventnote
----------------------- --------------------
2008-12-14 10:01:00.000 oo! an event!
2008-12-14 10:01:00.000 oo! an event!
2008-12-14 10:01:00.000 oo! an event!
2008-12-14 10:01:00.000 oo! an event!
2008-12-14 10:23:00.000 oo! an event!
2008-12-14 10:23:00.000 oo! an event!
2008-12-14 10:23:00.000 oo! an event!
2008-12-14 11:23:00.000 oo! an event!
2008-12-14 11:23:00.000 oo! an event!
2008-12-14 11:23:00.000 oo! an event!
2008-12-14 11:23:00.000 oo! an event!
2008-12-14 11:23:00.000 oo! an event!
2008-12-14 14:23:00.000 oo! an event!
2008-12-14 14:23:00.000 oo! an event!
2008-12-14 14:23:00.000 oo! an event!
2008-12-14 19:23:00.000 oo! an event!
2008-12-14 19:23:00.000 oo! an event!
2008-12-14 19:23:00.000 oo! an event!
2008-12-14 19:23:00.000 oo! an event!
2008-12-14 19:00:00.000 oo! an event!
2008-12-14 19:00:00.000 oo! an event!
2008-12-14 19:00:00.000 oo! an event!
22 Row(s) affected
然后我用LEFT OUTER JOIN将它们连接在一起,像这样:
select
dr.startdate,
dr.enddate,
count(me.eventdate) as eventcount
from
fn_daterange('12/14/2008 10:00:00', '12/14/2008 20:00:00', '01:00:00' ) dr
LEFT OUTER JOIN myevents me
on ( me.eventdate between dr.startdate and dr.enddate)
group by
dr.startdate,
dr.enddate
startdate enddate eventcount
----------------------- ----------------------- ----------
2008-12-14 10:00:00.000 2008-12-14 10:59:59.993 7
2008-12-14 11:00:00.000 2008-12-14 11:59:59.993 5
2008-12-14 12:00:00.000 2008-12-14 12:59:59.993 0
2008-12-14 13:00:00.000 2008-12-14 13:59:59.993 0
2008-12-14 14:00:00.000 2008-12-14 14:59:59.993 3
2008-12-14 15:00:00.000 2008-12-14 15:59:59.993 0
2008-12-14 16:00:00.000 2008-12-14 16:59:59.993 0
2008-12-14 17:00:00.000 2008-12-14 17:59:59.993 0
2008-12-14 18:00:00.000 2008-12-14 18:59:59.993 0
2008-12-14 19:00:00.000 2008-12-14 19:59:59.993 7
2008-12-14 20:00:00.000 2008-12-14 20:59:59.993 0
11 Row(s) affected
哇塞,这太棒了 - 我可以在工作中用它进行各种分析! :-)
感谢 Fred 的问题和 Dave 关于常见表查询信息的提供!
Ron