Get the timestamp 10 minutes earlier from now:

SELECT SYSTIMESTAMP - INTERVAL ‘10′ minute FROM DUAL;

Get the timestamp 1 year later from the specified timestamp:

SELECT timestamp’2004-02-29 00:00:00′ + INTERVAL ‘1′ year(1) FROM dual;

Extract fields from a timestamp:

SELECT
EXTRACT(year FROM current_timestamp) EY,
EXTRACT(month FROM current_timestamp) EM,
EXTRACT(day FROM current_timestamp) ED,
EXTRACT(hour FROM current_timestamp) EH,
EXTRACT(minute FROM current_timestamp) EM,
EXTRACT(second FROM current_timestamp) ES,
EXTRACT(timezone_hour FROM current_timestamp) TH,
EXTRACT(timezone_minute FROM current_timestamp) TM,
EXTRACT(timezone_region FROM current_timestamp) TR,
EXTRACT(timezone_abbr FROM current_timestamp ) TA
FROM dual;

More on: Oracle Timestamp Data Type

In Oracle/PLSQL, the NVL function lets you substitute a value when a null value is encountered.

The syntax for the NVL function is:

NVL( string1, replace_with )

string1 is the string to test for a null value.

replace_with is the value returned if string1 is null.