Oracle time-plus-Subtract statement notation

From:http://soft.doit.com.cn/article/2012/0105/2850851.shtml

--Addition

--plus 1 years
SELECT sysdate,add_months (sysdate,12) from DUAL;

--Add January
SELECT sysdate,add_months (sysdate,1) from DUAL;

--plus 1 weeks
SELECT Sysdate,to_char (sysdate+7, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

--plus 1 days
SELECT Sysdate,to_char (sysdate+1, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

--plus 1 hours
SELECT Sysdate,to_char (sysdate+1/24, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

--plus 1 minutes
SELECT Sysdate,to_char (sysdate+1/24/60, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

--plus 1 seconds
SELECT Sysdate,to_char (sysdate+1/24/60/60, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

--Subtraction

-Minus 1 years
SELECT sysdate,add_months (sysdate,-12) from DUAL;

--Minus January
SELECT sysdate,add_months (sysdate,-1) from DUAL;

-Minus 1 weeks
SELECT Sysdate,to_char (SYSDATE-7, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

-Minus 1 days
SELECT Sysdate,to_char (SYSDATE-1, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

-Minus 1 hours
SELECT Sysdate,to_char (sysdate-1/24, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

-Minus 1 minutes
SELECT Sysdate,to_char (sysdate-1/24/60, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

-Minus 1 seconds
SELECT Sysdate,to_char (sysdate-1/24/60/60, ' Yyyy-mm-dd HH24:MI:SS ') from DUAL;

Oracle time-plus-Subtract statement notation