Oracle 18c

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select * from V$VERSION;

BANNER
BANNER_FULL
BANNER_LEGACY
CON_ID

Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Version 18.4.0.0.0
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
0

select cast(to_timestamp('20190516 08:00:00', 'yyyymmdd HH24:MI:SS') as date) from dual

CAST(TO_TIMESTAMP('2019051608:00:00','YYYYMMDDHH24:MI:SS')ASDATE)

16-MAY-19

select  TO_CHAR(
               cast(to_timestamp('20190516 08:00:00', 'yyyymmdd HH24:MI:SS') as date)
                ,'yyyymmdd HH24:MI:SS') from dual

TO_CHAR(CAST(TO_TIMESTAMP('2019051608:00:00','YYYYMMDDHH24:MI:SS')ASDATE),'YYYYMMDDHH24:MI:SS')

20190516 08:00:00

select to_timestamp('20190516 08:00:00', 'yyyymmdd HH24:MI:SS') from dual;

TO_TIMESTAMP('2019051608:00:00','YYYYMMDDHH24:MI:SS')

16-MAY-19 08.00.00.000000000

select cast(cast(to_timestamp('20190516 08:00:00', 'yyyymmdd HH24:MI:SS') as date) as timestamp) from dual

CAST(CAST(TO_TIMESTAMP('2019051608:00:00','YYYYMMDDHH24:MI:SS')ASDATE)ASTIMESTAMP)

16-MAY-19 08.00.00.000000

select to_timestamp('20190516 08:00:00.123', 'yyyymmdd HH24:MI:SS.FF') from dual;

TO_TIMESTAMP('2019051608:00:00.123','YYYYMMDDHH24:MI:SS.FF')

16-MAY-19 08.00.00.123000000

select cast(to_timestamp('20190516 08:00:00.123', 'yyyymmdd HH24:MI:SS.FF') as date) 
from dual;

CAST(TO_TIMESTAMP('2019051608:00:00.123','YYYYMMDDHH24:MI:SS.FF')ASDATE)

16-MAY-19

select cast(cast(to_timestamp('20190516 08:00:00.123', 'yyyymmdd HH24:MI:SS.FF') as date) as timestamp) from dual

CAST(CAST(TO_TIMESTAMP('2019051608:00:00.123','YYYYMMDDHH24:MI:SS.FF')ASDATE)ASTIMESTAMP)

16-MAY-19 08.00.00.000000