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Time Variance Query - So close

Discussion in 'Databases' started by johnberman, Feb 18, 2017.

  1. #1
    My database contains a table which stores meteor events submitted by different contributors

    each event has a unique ID and other things stored are the date and time and contributor ID

    There can be many events on the same date and time submitted by different contributors, I want to write a query where it would bring back all records which match by date and time
    however as recording equipment may not by time synchronized accurately I wanted to be able to have a variance of plus or minus 30 seconds

    SELECT a.event_id, a.user_ID, a.`date`, a.`Time`
    FROM quadrantids_date AS a
    JOIN quadrantids_date AS b
    WHERE a.event_id != b.event_id
    AND a.`date` = b.`date`
    AND time_to_sec(a.`Time`) - time_to_sec(b.`Time`) BETWEEN -30 AND 30;​

    sample data shows the following (event ID, Contributor, Date, time)

    37776 2 2017-01-01 01:08:45
    47827 3 2017-01-01 01:09:07
    33501 1 2017-01-01 01:14:59
    47828 3 2017-01-01 01:15:00
    37779 2 2017-01-01 01:19:29
    37780 2 2017-01-01 01:19:36
    33503 1 2017-01-01 01:24:48
    33503 1 2017-01-01 01:24:48

    event 37779 and 37780 are within the 30 second rule but they are from the same contributor, ie contributor number 2 - Somehow these need to be removed

    also event 33503 its duplicated for some reason - in the main table events are unique so there is only 33505 - really dont understand why this is here

    Pointers really appreciated

    John B
    johnberman, Feb 18, 2017 IP
  2. Rukbat

    Rukbat Well-Known Member

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    ... AND time_to_sec BETWEEN (CONVERT('01:08:45' USING TIME) AND CONVERT('01:24:48' USING TIME));

    should work. You'll have to determine the min and max times (and account for 00:00:00 and 12:00:00 crossovers).
    Rukbat, Feb 28, 2017 IP