TO_CHAR(<x> [,<fmt >[,<nlsparm>] ])

SELECT TO_CHAR(SYSDATE,'Day Ddspth,Month YYYY'
,'NLS_DATE_LANGUAGE=German') Today_Heute
FROM dual;

SELECT TO_CHAR(SYSDATE
,'"On the "Ddspth" day of "Month, YYYY')
FROM dual;
这里的Dd和DD意思一样，不同点是单词首字母大写，其他小写

TO_CHAR(SYSDATE,'"ONTHE"DDSPTH"DAYOF"MONTH,Y
--------------------------------------------
On the Twenty-Seventh day of November , 2002

SP 数字的拼写 ---spelling out
TH 数字的序数词 
spth 使用序数词来拼写，如12--->twelve(sp方式) -->Twelfth (spth方式)

SELECT SYSDATE
,TO_CHAR(SYSDATE,'Mmspth') Month
,TO_CHAR(SYSDATE,'DDth') Day
,TO_CHAR(SYSDATE,'Yyyysp') Year
FROM dual;
SYSDATE     MONTH    DAY  YEAR
----------- -------- ---- -------------------------------------
01-DEC-1999 Twelfth 01ST One Thousand Nine Hundred Ninety-Nine

其中01ST是数字的序数词，Twelfth 是数字被拼写后的序数词
Yyyy就是YYYY，但是每个单词首字母大写，其他小写

SELECT TO_CHAR(SYSDATE,'MONTH') upperCase
,TO_CHAR(SYSDATE,'Month') mixedCase
,TO_CHAR(SYSDATE,'month') lowerCase
FROM dual;
UPPERCASE MIXEDCASE LOWERCASE
--------- --------- ---------
DECEMBER December december


Date Format Codes
Date Code     | Format Code Description     | Example
AD or BC        Epoch indicator              ‘YYYY AD’ = 2002 AD
A.D. or  B.C.   Epoch indicator with periods ‘YYYY A.D.’ = 2002 A.D.
AM or PM        Meridian indicator           ‘HH12AM’ = 09AM
A.M. or P.M.    Meridian indicator with periods ‘HH A.M.’= 09 A.M.
DY              Day of week abbreviated        Mon, Tue, Fri
DAY             Day of week spelled out        Monday, Tuesday, Friday
D               Day of week (1–7)             1,2,3,4,5,6,7
DD              Day of month (1–31)           1,2,3,4…31
DDD             Day of year (1–366)           1,2,3,4…366
FF              Fractional seconds             .34127
J               Julian day (days since 4712BC) 2451514,2451515,2451516
W               Week of the month (1–5)       1,2,3,4,5
WW, IW          Week of the year, ISO week of the year 1,2,3,4…53
MM              Two-digit month                01,02,03…12
MON             Month name abbreviated        Jan, Feb, Mar…Dec
MONTH           Month name spelled out        January, February…
Q               Quarter                       01-Jan-2002
RM              Roman numeral month (I–XII)  I,II,III,IV,V…XII
YYYY,YYY,       Four-digit year; last 3, 2, 1  1999, 999, 99, 9
 YY, Y          digits in the year             2000, 000, 00, 0
YEAR            Year spelled out              Two thousand two
SYYYY If BC,    year is shown as negative      -1250
RR              Used for data input with only  See description 
                two digits for the year        following table
HH, HH12        Hour of the half-day (1–12)   1,2,3…12
HH24            Hour of the day (0–23)        0,1,2…23
MI              Minutes of the hour (0–59)    0,1,2…59
SS              Seconds of the minute (0–59)  0,1,2…59
SSSSS           Seconds of the day (0–86399)  0,1,2…86399
TZD             Time zone daylight savings;    CST
                must correspond to TZR         
TZH             Time zone hour, together        07
                with TZM is time zone offset
TZM             Time zone minute, together      00
                with TZH is time zone offset   
TZR             Time zone region          US/Central, Mexico/BajaNorte
, . / - ; :     Punctuation                    Literal display
‘text’          Quoted text Literal             display



SELECT TO_CHAR(123456,'9.99EEEE')
,TO_CHAR(123456,'9.9EEEE')
FROM dual;
TO_CHAR(12 TO_CHAR(1
---------- ---------
1.23E+05 1.2E+05


SELECT TO_CHAR(-1234.56,'C099G999D99MI','NLS_NUMERIC_CHARACTERS='',.''
NLS_CURRENCY=''DM''NLS_ISO_CURRENCY=''GERMANY''') Balance
FROM dual;

BALANCE
--------------
DEM001.234,56-

其中C 代表使用ISO international currency symbol (format symbol C).
For example, the NLS_CURRENCY symbol for U.S. dollars is $, but this
symbol is not uniquely American, so the ISO symbol for U.S. dollars is USD.


Numeric
 Cod