MySQL convert timediff output to day, hour, minute, second format

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.

Try

SELECT @s:='2016-03-01' started, @e:= '2018-04-21' ended, 
FLOOR((@ms:=TIMESTAMPDIFF(MONTH,@s,@e))/12) yrs, (@ms%12) mns, 
@d:=TIMESTAMPDIFF(DAY,@s:=DATE_ADD(@s,INTERVAL @ms MONTH), @e) dys,
@hr:=TIMESTAMPDIFF(HOUR,@s:=DATE_ADD(@s, INTERVAL @d DAY),@e) hrs,
TIMESTAMPDIFF(MINUTE,TIMESTAMPADD(HOUR,@hr,@s),@e) mins;

This will give you a breakdown from year, month, day, hour and minutes between two dates.

Hope it assists someone.

I used the answer given by Bodgans, but I added a condition to insert a 0 before quantities less than 10.

CONCAT(
  IF(FLOOR(TIMESTAMPDIFF(SECOND, startDate, endDate) / 86400) < 10, '0', ''),    FLOOR(TIMESTAMPDIFF(SECOND, startDate, endDate) / 86400), ' days ',
  IF(FLOOR((TIMESTAMPDIFF(SECOND, startDate, endDate) % 86400)/3600) < 10, '0', ''), FLOOR((TIMESTAMPDIFF(SECOND, startDate, endDate) % 86400)/3600), ' hours ',
  IF(FLOOR((TIMESTAMPDIFF(SECOND, startDate, endDate) % 3600)/60) < 10, '0', ''), FLOOR((TIMESTAMPDIFF(SECOND, startDate, endDate) % 3600)/60), ' minutes ',
  IF((TIMESTAMPDIFF(SECOND, startDate, endDate) % 60) < 10, '0', ''), (TIMESTAMPDIFF(SECOND, startDate, endDate) % 60),  ' seconds'
)

In that way, we can get a result as follows

09 days 10 hours 06 minutes 30 seconds

SELECT 
CONCAT(
TIMESTAMPDIFF(day,'2001-01-01 00:00:00','2001-01-02 23:10:00') , ' dagen ',
MOD( TIMESTAMPDIFF(hour,'2001-01-01 00:00:00','2001-01-02 23:10:00'), 24), ' uren ',
MOD( TIMESTAMPDIFF(minute,'2001-01-01 00:00:00','2001-01-02 23:10:00'), 60), ' minuten '
)