SELECT CONCAT(
FLOOR(HOUR(TIMEDIFF('2010-01-06 08:46', '2010-01-01 12:30')) / 24), ' days ',
MOD(HOUR(TIMEDIFF('2010-01-06 08:46', '2010-01-01 12:30')), 24), ' hours ',
MINUTE(TIMEDIFF('2010-01-06 08:46', '2010-01-01 12:30')), ' minutes')
Use your end_time and start_time for the fixed datetime values in my example
As per the two comments below, this solution only works for date differences within 35 days. If you know there are more than 35 days between start and end, i.e. differences over a month, don't use it. Other answers here using TIMESTAMPDIFF will work.
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