Oracle Function：TO_CHAR

Posted 2020-09-26

Description

The Oracle/PLSQL TO_CHAR function converts a number or date to a string.将数字转换为日期或字符串

Syntax

TO_CHAR( value [, format_mask] [, nls_language] )

Parameters or Arguments

Value	A number or date that will be converted to a string.
format_mask	Optional. This is the format that will be used to convert value to a string.
nls_language	Optional. This is the nls language used to convert value to a string.

Example

Numbers

TO_CHAR(1210.73, ‘9999.9‘) Result: ‘ 1210.7‘ TO_CHAR(-1210.73, ‘9999.9‘) Result: ‘-1210.7‘ TO_CHAR(1210.73, ‘9,999.99‘) Result: ‘ 1,210.73‘ TO_CHAR(1210.73, ‘$9,999.00‘) Result: ‘ $1,210.73‘ TO_CHAR(21, ‘000099‘) Result: ‘ 000021‘

Dates

TO_CHAR(sysdate, ‘yyyy/mm/dd‘) Result: ‘2003/07/09‘ TO_CHAR(sysdate, ‘Month DD, YYYY‘) Result: ‘July 09, 2003‘ TO_CHAR(sysdate, ‘FMMonth DD, YYYY‘) Result: ‘July 9, 2003‘ TO_CHAR(sysdate, ‘MON DDth, YYYY‘) Result: ‘JUL 09TH, 2003‘ TO_CHAR(sysdate, ‘FMMON DDth, YYYY‘) Result: ‘JUL 9TH, 2003‘ TO_CHAR(sysdate, ‘FMMon ddth, YYYY‘) Result: ‘Jul 9th, 2003‘   "FM":This means that zeros and blanks are suppressed(压制).

The following is a list of valid parameters when the TO_CHAR function is used to convert a date to a string.

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
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.

Frequently Asked Questions

Question: Why doesn‘t this sort the days of the week in order?	Answer: In the above SQL, the fmDay format mask used in the TO_CHAR function will return the name of the Day and not the numeric value of the day. To sort the days of the week in order, you need to return the numeric value of the day by using the fmD format mask as follows:
SELECT ename, hiredate, TO_CHAR((hiredate),‘fmDay‘) "Day" FROM emp ORDER BY "Day";	SELECT ename, hiredate, TO_CHAR((hiredate),‘fmD‘) "Day" FROM emp ORDER BY "Day";