[英]delete records in time ranges in SQL Server
I have a lot of time ranges in TimeRanges table: 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
and I have some filters in TimeFilters table: 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
What I need is to delete the records from TimeRanges table, only those time ranges that are within the TimeFilters table will be retained. 我需要从TimeRanges表中删除记录,仅保留TimeFilters表中的那些时间范围。
To simply put, I want the following records retained: from 2010-02-01 00:00 to 2010-03-01 00:00, like: 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
from 2011-02-01 00:00 to 2011-03-01 00:00, like: 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
What I can do now is to select those records are within TimeFilters into a temporary table, then truncate the TimeRanges table, and put back records from the temporary table, but that's quite time consuming. 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。
To delete all the records in TimeRanges
that do not have a match in TimeFilters
, you can do 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
The tricky thing here is to do a left join
, and delete those TimeRanges
that do not have a correspondent filter (when f.startTime
or f.endTime
are 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)
After deleting, you can see the results: 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)
What you can do is an outer join to get both the matches and the non-matches and then have a condition to extract the non-matches: 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
I don't know if the rest can be done with MySQL, but what you'll want to do is generate a condition that matches each each row that didn't fall between the dates in the filter table. 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。 The pseudo code to do this would be as follows: 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;
If this can't be done using MySql, then it can be done using a scripting language, such as PHP. 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。
I assume you have some sort of ID column on your TimeRanges table? 我假设您的TimeRanges表上有某种ID列? If so, would something like this work for you? 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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