1.字符串与日期间转换
date '2007-05-10' cast( (curent_timestamp() (format 'YYYYMMDDHHMISS') )as varchar()) //结果为20180615164201
2.毫秒转换为时间戳
select cast (to_timestamp(cast(/ as BIGINT)) as date); //结果为2018-05-03 02:21:03.000000
注解:日期从1970-01-01开始的,Unix诞生日期,做为计算机时间原点。