三大数据库时间戳相减得分钟秒数

sqlserver时间戳：

日期转时间戳：SELECT DATEDIFF(S,'2019-05-10 09:49:59.100', GETDATE());
日期转时间戳：SELECT DATEDIFF(S,'2019-05-12 10:49:59.900', GETDATE());

相减分钟：SELECT (DATEDIFF(S,'2019-05-10 09:49:59.100', GETDATE())-DATEDIFF(S,'2019-05-12 10:49:59.900', GETDATE()))/60；

相减秒数：SELECT (DATEDIFF(S,'2019-05-10 09:49:59.100', GETDATE())-DATEDIFF(S,'2019-05-12 10:49:59.900', GETDATE()))；

myql时间戳相减：

相减分钟：select timestampdiff(SECOND,'2015-05-04 12:00','2015-05-04 12:01:30')/60;

相减秒数：select timestampdiff(SECOND,'2015-05-04 12:00','2015-05-04 12:01:30');

postgresql时间戳相减：

相减分钟：SELECT (EXTRACT(epoch FROM NOW())-EXTRACT(epoch FROM CAST('2017-12-06 00:17:10' AS TIMESTAMP)))/60;

相减秒数：SELECT EXTRACT(epoch FROM NOW())-EXTRACT(epoch FROM CAST('2017-12-06 00:17:10' AS TIMESTAMP));