delete records in time ranges in SQL Server

Question

I have a lot of time ranges in TimeRanges table:

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:

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.

To simply put, I want the following records retained: from 2010-02-01 00:00 to 2010-03-01 00:00, like:

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:

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.

Answer 1

To delete all the records in TimeRanges that do not have a match in TimeFilters, you can do

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)

After deleting, you can see the results:

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)

Answer 2

I assume you have some sort of ID column on your TimeRanges table? If so, would something like this work for you?

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 )

Answer 3

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:

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. The pseudo code to do this would be as follows:

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.