Date Functions

Oracle stores date in an internal numeric number
The default date and input format for any date is DD-MON-YY.
If you want to change the default date time then ,Set default datetime format in string literals by running below quer.

ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MM-YYYY';

SQL date functions are:

	Oracle
1	ADD_MONTHS	Add specified number of months
2	EXTRACT for Datetime	Extract day, month, year etc from datetime
3	LAST_DAY	Get last date of month
4	MONTHS_BETWEEN	Get number of months between two dates
5	TO_CHAR for Datetime	Convert datetime to string
6	TO_DATE	Convert string to datetime
7	TRUNC for Datetime	Truncate datetime