--0
select datediff(now(), now());
--2
select datediff('2015-04-22 23:59:00', '2015-04-20 00:00:00');
--2
select datediff('2015-04-22 00:00:00', '2015-04-20 23:59:00');
--1
select TIMESTAMPDIFF(DAY, '2015-04-20 23:59:00', '2015-04-22 00:00:00');
--2
select TIMESTAMPDIFF(DAY, '2015-04-20 00:00:00', '2015-04-22 00:00:00');
--2
select TIMESTAMPDIFF(DAY, '2015-04-20 00:00:00', '2015-04-22 12:00:00');
--2
select TIMESTAMPDIFF(DAY, '2015-04-20 00:00:00', '2015-04-22 23:59:00');
--71
select TIMESTAMPDIFF(HOUR, '2015-04-20 00:00:00', '2015-04-22 23:00:00');
--4260
select TIMESTAMPDIFF(MINUTE, '2015-04-20 00:00:00', '2015-04-22 23:00:00');