ORACLE to_char函数详解

 The following are number examples for the to_char function.
to_char(1210.73, '9999.9')
would return '1210.7'
to_char(1210.73, '9,999.99')
would return '1,210.73'
to_char(1210.73, '$9,999.00')
would return '$1,210.73'
to_char(21, '000099')
would return '000021'
The following is a list of valid parameters when the to_char function is used to convert a date to a string. These parameters can be used in many combinations.
 
ParameterExplanation
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
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.
The following are date examples for the to_char function.
to_char(sysdate, 'yyyy/mm/dd');
would return '2003/07/09'
to_char(sysdate, 'Month DD, YYYY');
would return 'July 09, 2003'
to_char(sysdate, 'FMMonth DD, YYYY');
would return 'July 9, 2003'
to_char(sysdate, 'MON DDth, YYYY');
would return 'JUL 09TH, 2003'
to_char(sysdate, 'FMMON DDth, YYYY');
would return 'JUL 9TH, 2003'
to_char(sysdate, 'FMMon ddth, YYYY');
would return 'Jul 9th, 2003'
You will no