1、to_date():字符串转为指定格式的日期数据
select to_date('2005-01-01 13:14:20','yyyy/mm/dd HH24:mi:ss') from dual; --2005/1/1 13:14:20
时间相关计算:
select (sysdate-to_date('2020/9/8 11:36:37','yyyy/mm/dd HH24:mi:ss'))*24 hh from dual; --计算小时差
select (sysdate-to_date('2020/9/8 11:36:37','yyyy/mm/dd HH24:mi:ss'))*24*60 mi from dual; --计算分钟差
select (sysdate-to_date('2020/9/8 11:36:37','yyyy/mm/dd HH24:mi:ss'))*24*60*60 ss from dual; --计算秒差