ORACLE- Difference between Date format ‘DD-Mon-YY’ and ‘DD-Mon-RR’

The ‘DD-Mon-YY’ format always specifies the two digit year as the current century. So when we specify ’25-May-08’ then the year is translate as 2008.

The ‘DD-Mon-RR’ format is the default format in ORACLE databases. Here the two digit year will be translated as below.

		If the specified two-digit year is:
		00-49	50-99
If two digits of the current year are:	00-49	The return date is in the current century	The return date is in the century before the current one
	50-99	The return date is in the century after the current one	The return date is in the current century

Example:

CREATE TABLE test_date(
colA DATE,
colB NUMBER);

INSERT INTO test_date
VALUES (TO_DATE('22-Dec-98','DD-Mon-YY'),4);

COMMIT;

INSERT INTO test_date
VALUES (TO_DATE('22-Dec-98','DD-Mon-RR'),5);
COMMIT;

So when we use formats for date in ORACLE databases we need to make sure that we are using the correct format.