Oracle 计算时间格式平均值的sql 语句

select to_char((to_date('2019-07-01', 'yyyy-mm-dd') + numtodsinterval(avg(begin_time_second), 'second')),'hh24:mi:ss') avg_begin_time,to_char((to_date('2019-07-01', 'yyyy-mm-dd') + numtodsinterval(avg(end_time_second), 'second')),'hh24:mi:ss') avg_end_time--2019-07-01 00:00:00 + numtodsinterval(平均数,'秒')转换为日期格式，然后再转换为 时间字符格式from (　　select 　　--把上班时间换算为秒　　to_char(a.actontime, 'hh24') * 3600 +　　to_char(a.actontime, 'mi') * 60 +　　to_char(a.actontime, 'ss') as begin_time_second,　　--把下班时间换算为秒 　　to_char(a.actofftime, 'hh24') * 3600 +　　to_char(a.actofftime, 'mi') * 60 + 　　to_char(a.actofftime, 'ss') as end_time_second　　from empworkdate a)

--获取年select to_char(sysdate,'yyyy') from dual--2016select to_char(sysdate,'YYYY') from dual--2016--获取月select to_char(sysdate,'mm') from dual--10select to_char(sysdate,'MM') from dual--10--获取日select to_char(sysdate,'dd') from dual--10select to_char(sysdate,'DD') from dual--10--获取时select to_char(sysdate,'hh24') from dual--15select to_char(sysdate,'hh') from dual--03select to_char(sysdate,'HH') from dual--03select to_char(sysdate,'HH24') from dual--15--获取分钟select to_char(sysdate,'MI') from dual--14select to_char(sysdate,'mi') from dual--14--获取秒select to_char(sysdate,'ss') from dual--35select to_char(sysdate,'SS') from dual--40--获取年月日时分秒select to_char(sysdate,'yyyy-mm-dd hh:mi:ss') from dual--2016-10-10 03:17:25select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual--2016-10-10 15:17:51