loadtime=20181112111111
to_char(to_date(loadtime, 'yyyy-mm-dd hh24:mi:ss'), 'yyyy-mm-dd hh24:mi:ss')
2018-11-12 11:11:11
number轉date
to_date(to_char(y.time,'99999999999999'), 'yyyy-mm-dd hh24:mi:ss')
varchar2轉換成number
to_number (to_char('20170728000000', '99999999999999'))