How to combine two rows and calculate the time difference between two timestamp values in MySQL?

Question

I have a situation that I\'m sure is quite common and it\'s really bothering me that I can\'t figure out how to do it or what to search for to find a relevant example/soluti

Answer 1

I believe this could be a simpler way to reach your goal:

SELECT
    start_log.name,
    MAX(start_log.ts) AS start_time,
    end_log.ts AS end_time,
    TIMEDIFF(MAX(start_log.ts), end_log.ts)
FROM
    log AS start_log
INNER JOIN
    log AS end_log ON (
            start_log.name = end_log.name
        AND
            end_log.ts > start_log.ts)
WHERE start_log.eventtype = 'start'
AND end_log.eventtype = 'stop'
GROUP BY start_log.name

It should run considerably faster as it eliminates one subquery.