sql计算字符串类型是时间差

需要用MySQL计算时间差，使用TIMESTAMPDIFF、DATEDIFF，记录一下实验结果

--1.默认计算天数
select datediff('2020-09-08 23:59:00', '2020-09-10 00:00:00');
select datediff('2020-09-10 00:00:00', '2020-09-08 23:59:00');
--2.按照天数计算
select TIMESTAMPDIFF(DAY, '2020-09-08 22:00:00', '2020-09-10 00:00:00');
--3.按照小时计算
select TIMESTAMPDIFF(HOUR, '2020-09-08 22:00:00', '2020-09-10 00:00:00');
--4.按照分钟计算
select TIMESTAMPDIFF(MINUTE, '2020-09-08 22:00:00', '2020-09-10 00:00:00');
--5.按照秒计算
select TIMESTAMPDIFF(SECOND, '2020-09-08 22:00:00', '2020-09-10 00:00:00');