Oracle compute time format average

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 (average, ‘seconds’) is converted to date format and then to time character format
from
(
　　select
— convert working hours to seconds
　　to_char(a.actontime, ‘hh24’) * 3600 +
　　to_char(a.actontime, ‘mi’) * 60 +
　　to_char(a.actontime, ‘ss’) as begin_time_second,
— convert off hours to seconds
　　to_char(a.actofftime, ‘hh24’) * 3600 +
　　to_char(a.actofftime, ‘mi’) * 60 +
　　to_char(a.actofftime, ‘ss’) as end_time_second
　　from empworkdate a
)