Plsql date

To use the current date use sysdate

select sysdate from dual;

To specify a date.

Parameter 	Explanation
YEAR 	Year, spelled out
YYYY 	4-digit year
YYY
YY
Y 	Last 3, 2, or 1 digit(s) of year.
IYY
IY
I 	Last 3, 2, or 1 digit(s) of ISO year.
IYYY 	4-digit year based on the ISO standard
RRRR 	Accepts a 2-digit year and returns a 4-digit year.
A value between 0-49 will return a 20xx year.
A value between 50-99 will return a 19xx year.
Q 	Quarter of year (1, 2, 3, 4; JAN-MAR = 1).
MM 	Month (01-12; JAN = 01).
MON 	Abbreviated name of month.
MONTH 	Name of month, padded with blanks to length of 9 characters.
RM 	Roman numeral month (I-XII; JAN = I).
WW 	Week of year (1-53) where week 1 starts on the first day of the year and continues to the seventh day of the year.
W 	Week of month (1-5) where week 1 starts on the first day of the month and ends on the seventh.
IW 	Week of year (1-52 or 1-53) based on the ISO standard.
D 	Day of week (1-7).
DAY 	Name of day.
DD 	Day of month (1-31).
DDD 	Day of year (1-366).
DY 	Abbreviated name of day.
J 	Julian day; the number of days since January 1, 4712 BC.
HH 	Hour of day (1-12).
HH12 	Hour of day (1-12).
HH24 	Hour of day (0-23).
MI 	Minute (0-59).
SS 	Second (0-59).
SSSSS 	Seconds past midnight (0-86399).
FF 	Fractional seconds. Use a value from 1 to 9 after FF to indicate the number of digits in the fractional seconds. 
AD or A.D 	AD indicator
BC or B.C. 	BC indicator
TZD 	Daylight savings information. For example, 'PST'
TZH 	Time zone hour.
TZM 	Time zone minute.
TZR 	Time zone region.

to_date('2003/07/09', 'yyyy/mm/dd')
to_date('070903', 'MMDDYY')
to_date('20020315', 'yyyymmdd')