Addition and subtraction of Oracle Date and Time

Addition
Select sysdate, add_months (sysdate, 12) from dual; -- add 1 year
Select sysdate, add_months (sysdate, 1) from dual; -- add January
Select sysdate, to_char (sysdate + 7, 'yyyy-mm-dd hh24: MI: ss') from dual; -- add 1 week
Select sysdate, to_char (sysdate + 1, 'yyyy-mm-dd hh24: MI: ss') from dual; -- add 1 day
Select sysdate, to_char (sysdate + 1/24, 'yyyy-mm-dd hh24: MI: ss') from dual; -- add 1 hour
Select sysdate, to_char (sysdate + 1/24/60, 'yyyy-mm-dd hh24: MI: ss') from dual; -- add 1 minute
Select sysdate, to_char (sysdate + 1/24/60/60, 'yyyy-mm-dd hh24: MI: ss') from dual; -- add 1 second

Subtraction
Select sysdate, add_months (sysdate,-12) from dual; -- minus 1 year
Select sysdate, add_months (sysdate,-1) from dual; -- minus January
Select sysdate, to_char (sysdate-7, 'yyyy-mm-dd hh24: MI: ss') from dual; -- minus 1 week
Select sysdate, to_char (sysdate-1, 'yyyy-mm-dd hh24: MI: ss') from dual; -- minus 1 day
Select sysdate, to_char (sysdate-1/24, 'yyyy-mm-dd hh24: MI: ss') from dual; -- minus 1 hour
Select sysdate, to_char (sysdate-1/24/60, 'yyyy-mm-dd hh24: MI: ss') from dual; -- minus 1 minute
Select sysdate, to_char (sysdate-1/24/60/60, 'yyyy-mm-dd hh24: MI: ss') from dual; -- minus 1 second