[英]delete records in time ranges in SQL Server
我在TimeRanges表中有很多时间范围:
StartTime EndTime
2010-01-01 06:00 2010-01-01 18:00
2010-01-01 20:00 2010-01-01 22:00
2010-01-02 06:00 2010-01-02 18:00
2010-01-02 20:00 2010-01-02 22:00
2010-01-03 06:00 2010-01-03 18:00
2010-01-03 20:00 2010-01-03 22:00
2010-01-04 06:00 2010-01-04 18:00
2010-01-04 20:00 2010-01-04 22:00
...
...
2010-02-01 06:00 2010-02-01 18:00
2010-02-01 20:00 2010-02-01 22:00
2010-02-02 06:00 2010-02-02 18:00
2010-02-02 20:00 2010-02-02 22:00
2010-02-03 06:00 2010-02-03 18:00
2010-02-03 20:00 2010-02-03 22:00
2010-02-04 06:00 2010-02-04 18:00
2010-02-04 20:00 2010-02-04 22:00
...
...
2011-01-01 06:00 2011-01-01 18:00
2011-01-01 20:00 2011-01-01 22:00
2011-01-02 06:00 2011-01-02 18:00
2011-01-02 20:00 2011-01-02 22:00
2011-01-03 06:00 2011-01-03 18:00
2011-01-03 20:00 2011-01-03 22:00
2011-01-04 06:00 2011-01-04 18:00
2011-01-04 20:00 2011-01-04 22:00
...
...
2011-02-01 06:00 2011-02-01 18:00
2011-02-01 20:00 2011-02-01 22:00
2011-02-02 06:00 2011-02-02 18:00
2011-02-02 20:00 2011-02-02 22:00
2011-02-03 06:00 2011-02-03 18:00
2011-02-03 20:00 2011-02-03 22:00
2011-02-04 06:00 2011-02-04 18:00
2011-02-04 20:00 2011-02-04 22:00
而且我在TimeFilters表中有一些过滤器:
StartTime EndTime
2010-02-01 00:00 2010-03-01 00:00
2011-02-01 00:00 2011-03-01 00:00
2012-02-01 00:00 2012-03-01 00:00
我需要从TimeRanges表中删除记录,仅保留TimeFilters表中的那些时间范围。
简而言之,我希望保留以下记录:从2010-02-01 00:00到2010-03-01 00:00,例如:
2010-02-01 06:00 2010-02-01 18:00
2010-02-01 20:00 2010-02-01 22:00
2010-02-02 06:00 2010-02-02 18:00
2010-02-02 20:00 2010-02-02 22:00
2010-02-03 06:00 2010-02-03 18:00
2010-02-03 20:00 2010-02-03 22:00
2010-02-04 06:00 2010-02-04 18:00
2010-02-04 20:00 2010-02-04 22:00
从2011-02-01 00:00到2011-03-01 00:00,例如:
2011-02-01 06:00 2011-02-01 18:00
2011-02-01 20:00 2011-02-01 22:00
2011-02-02 06:00 2011-02-02 18:00
2011-02-02 20:00 2011-02-02 22:00
2011-02-03 06:00 2011-02-03 18:00
2011-02-03 20:00 2011-02-03 22:00
2011-02-04 06:00 2011-02-04 18:00
2011-02-04 20:00 2011-02-04 22:00
我现在能做的是选择那些在TimeFilters中的记录到一个临时表中,然后截断TimeRanges表,并从该临时表中放回记录,但这很费时间。
要删除TimeRanges
中在TimeFilters
不匹配的所有记录,您可以执行
delete TimeRanges
from TimeRanges r
left join timefilters f on r.StartTime >= f.StartTime and r.EndTime <= f.EndTime
where f.StartTime is null
棘手的事情是进行left join
,并删除那些没有对应过滤器的TimeRanges
(当f.startTime
或f.endTime
为null时)
删除后,您可以看到结果:
select *
from TimeRanges
StartTime EndTime
----------------------- -----------------------
2010-02-01 06:00:00.000 2010-02-01 18:00:00.000
2010-02-01 20:00:00.000 2010-02-01 22:00:00.000
2010-02-02 06:00:00.000 2010-02-02 18:00:00.000
2010-02-02 20:00:00.000 2010-02-02 22:00:00.000
2010-02-03 06:00:00.000 2010-02-03 18:00:00.000
2010-02-03 20:00:00.000 2010-02-03 22:00:00.000
2010-02-04 06:00:00.000 2010-02-04 18:00:00.000
2010-02-04 20:00:00.000 2010-02-04 22:00:00.000
2011-02-01 06:00:00.000 2011-02-01 18:00:00.000
2011-02-01 20:00:00.000 2011-02-01 22:00:00.000
2011-02-02 06:00:00.000 2011-02-02 18:00:00.000
2011-02-02 20:00:00.000 2011-02-02 22:00:00.000
2011-02-03 06:00:00.000 2011-02-03 18:00:00.000
2011-02-03 20:00:00.000 2011-02-03 22:00:00.000
2011-02-04 06:00:00.000 2011-02-04 18:00:00.000
2011-02-04 20:00:00.000 2011-02-04 22:00:00.000
(16 row(s) affected)
您可以做的是使用外部联接来获取匹配项和不匹配项,然后有一个条件来提取不匹配项:
select * form TimeRanges r join TimeFilters f on
r.StartTime between f.StartTime and f.EndTime and
r.EndTime between f.StartTime and f.EndTime
where f.StartTime is null and f.EndTime is null
我不知道其余的事情是否可以用MySQL完成,但是您想要做的是生成一个条件,该条件匹配不在过滤表中日期之间的每一行。 为此的伪代码如下:
cond='';
while (r = read row) do
if (cond=='') {
sep='';
} else {
sep=' OR ';
}
cond = cond . sep .
'(r.StartDate=' . r->StartDate . ' and r.EndDate=' . r->EndDate . ')';
}
# Before running the delete query comment it out and run the query printed by:
# print 'select * from TimeRanges where '.cond;
run query 'delete from TimeRanges where '.cond;
如果使用MySql无法完成此操作,则可以使用脚本语言(例如PHP)来完成。
我假设您的TimeRanges表上有某种ID列? 如果是这样,这样的事情对您有用吗?
DELETE
TimeRanges
WHERE
id NOT IN ( SELECT
tr.id
FROM
TimeRanges tr
JOIN TimeFilter tf ON tr.startdate >= tf.startdate AND
tr.enddate <= tf.enddate )
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