Term: TO_DATE

Definition:
The Oracle TO_DATE function will convert either a character string or an expression into a date value.

Example Syntax
These all show valid date formats for "February 16th, 2009":

to_date('16-Feb-09', 'DD-Mon-YY')

to_date('02/16/09', 'MM/DD/YY')

to_date('021609', 'MMDDYY')

to_date('16-Feb-09', 'DD-Mon-YY HH:MI:SS') 

to_date('Feb/16/09', 'Mon/DD/YY HH:MI:SS')

to_date('February.16.2009', 'Month.DD.YYYY HH:MI:SS')

The 'format' string must be a valid DATE format: YYYY=year, MM=month, DD=Day, HH=Hour, Mi=Minute
If no format is specified Oracle will assume the default date format has been supplied in char.

Note that the return value of TO_DATE can be influenced by setting the NLS_DATE_LANGUAGE and NLS_CALENDAR parameters.

TO_DATE Format Masks
Format	Returns
D	Day of the week
DD	Day of the month
DDD	Numerical day of the year, 1 ~ 365 (366 for Leap years)
DAY	Full textual representation of the day, i.e. "Monday", "Tuesday", "Wednesday"
DY	Day in three letters, i.e. "MON", "TUE", "FRI"
W	Week of the month
WW	Week of the year
MM	Month in two digits, i.e. 01 = Jan, 02 = Feb,...12 = -Dec
MON	Month in three characters, i.e. "Jan", "Feb", "Apr"
MONTH	Full textual representation of the Month, i.e. "January", "February", "April"
RM	Month in Roman Characters (I-XII, I-Jan, II-Feb, ... XII-Dec)
Q	Quarter of the Month
YY	Last two digits of the year.
YYYY	Full year
YEAR	Year in words like "Nineteen Eighty Seven"
HH	Hours in 12 hour format
HH12	Hours in 12 hour format
HH24	Hours in 24 hour format ("military time")
MI	Minutes
SS	Seconds
FF	Fractional Seconds
SSSSS	Milliseconds
J	Julian Day i.e Days since 1^st-Jan-4712BC to till-date
RR	If the year is less than 50 then Oracle considers the year as a 21^st century date. If the year is greater than 50 then Oracle considers the year to be in the 20^th century.