我们都知道日期型的Oracle倒时是可以提供好的处理方案,也可以把相关日期做成实际数值型，.在后To_char就可以显示出我们所需要的相关类型。以下就是相关内容的详细介绍，希望你会有所收获。

to_char(1210.73,'9999.9')wouldreturn'1210.7' 
to_char(1210.73,'9,999.99')wouldreturn'1,210.73' 
to_char(1210.73,'$9,999.00')wouldreturn'$1,210.73' 
to_char(21,'000099')wouldreturn'000021' 
Thefollowingisalistofvalidparameterswhenthe
to_charfunctionisusedtoconvertadatetoastring.
Theseparameterscanbeusedinmanycombinations. 
ParameterExplanation 
YEARYear,spelledout 
YYYY4-digityear 
YYY 
YY 
YLast3,2,or1digit(s)ofyear. 
IYY 
IY 
ILast3,2,or1digit(s)ofISOyear. 
IYYY4-digityearbasedontheISOstandard 
QQuarterofyear(1,2,3,4;JAN-MAR=1). 
MMMonth(01-12;JAN=01). 
MONAbbreviatednameofmonth. 
MONTHNameofmonth,paddedwithblankstolengthof
9characters. 
RMRomannumeralmonth(I-XII;JAN=I). 
WWWeekofyear(1-53)whereweek1startsonthe
firstdayoftheyearandcontinuestotheseventh
dayoftheyear. 
WWeekofmonth(1-5)whereweek1startsonthe
firstdayofthemonthandendsontheseventh. 
IWWeekofyear(1-52or1-53)basedontheISO
standard. 
DDayofweek(1-7). 
DAYNameofday. 
DDDayofmonth(1-31). 
DDDDayofyear(1-366). 
DYAbbreviatednameofday. 
JJulianday;thenumberofdayssinceJanuary
1,4712BC. 
HHHourofday(1-12). 
HH12Hourofday(1-12). 
HH24Hourofday(0-23). 
MIMinute(0-59). 
SSSecond(0-59). 
SSSSSSecondspastmidnight(0-86399). 
FFFractionalseconds. 
Thefollowingaredateexamplesfortheto_charfunction. 
to_char(sysdate,'yyyy/mm/dd');wouldreturn'2003/07/09' 
to_char(sysdate,'MonthDD,YYYY');wouldreturn'July09,2003' 
to_char(sysdate,'FMMonthDD,YYYY');wouldreturn'July9,2003' 
to_char(sysdate,'MONDDth,YYYY');wouldreturn'JUL09TH,2003' 
to_char(sysdate,'FMMONDDth,YYYY');wouldreturn'JUL9TH,2003' 
to_char(sysdate,'FMMonddth,YYYY');wouldreturn'Jul9th,2003' 
Youwillnoticethatinsomeexamples,theformat_maskparameterbegins
with"FM".Thismeansthatzerosandblanksaresuppressed.Thiscanbeseenintheexamplesbelow. 
to_char(sysdate,'FMMonthDD,YYYY');wouldreturn'July9,2003' 
to_char(sysdate,'FMMONDDth,YYYY');wouldreturn'JUL9TH,2003' 
to_char(sysdate,'FMMonddth,YYYY');wouldreturn'Jul9th,2003' 
Thezeroshavebeensuppressedsothatthedaycomponentshowsas"9"asopposedto"09". 

Oracle函数to_char转化数字型指定小数点位数的用法

Oracle to_char，函数功能，就是将数值型或者日期型转化为字符型。

比如最简单的应用：

/*1.0123--->'1.0123'*/ 
SelectTO_CHAR(1.0123)FROMDUAL 
/*123--->'123'*/ 
SelectTO_CHAR(123)FROMDUAL 

接下来再看看下面：

/*0.123--->'.123'*/ 
SELECTO_CHAR(0.123)FROMDUAL 

上面的结果 ‘.123’ 在大多数情况下都不是我们想要的结果，我们想要的应该是 ‘0.123’。

我们来看一下to_char函数的具体用法：

TO_CHAR(n[,fmt[,'nlsparam']])

该函数将NUMBER类型的n按数值格式fmt转换成VARCHAR2类型的值。’nlsparams’指定由数值格式的元素返回的字符,包括:

．小数点字符

．组分隔符

．本地钱币符号

．国际钱币符号

变元的形式为：

'NLS_NUMERIC_CHARACTERS="dg"NLS_CURRENCY="tcxt"
NLS_ISO_CURRENCY=territory'

其中d为小数点字符,g为组分隔符。

例 :

TO_CHAR(17145,'L099G999','NLS_NUMERIC_CHARACTERS=
".,"NLS_CURRENCY="NUD"')=NUD017,145