Oracle to_char的用法


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.

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.

 

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 notice that in some examples, the format_mask parameter begins with "FM". This means that zeros and blanks are suppressed. This can be seen in the examples below.

to_char(sysdate, 'FMMonth DD, YYYY'); would return 'July 9, 2003'
to_char(sysdate, 'FMMON DDth, YYYY'); would return 'JUL 9TH, 2003'
to_char(sysdate, 'FMMon ddth, YYYY'); would return 'Jul 9th, 2003'

The zeros have been suppressed so that the day component shows as "9" as opposed to "09".

Oracle函數to_char轉化數字型指定小數點位數的用法

to_char,函數功能,就是將數值型或者日期型轉化為字符型。

比如最簡單的應用:

/*1.0123--->'1.0123'*/ 
Select TO_CHAR(1.0123) FROM DUAL 
/*123--->'123'*/ 
Select TO_CHAR(123) FROM DUAL

 接下來再看看下面:

/*0.123 ---> '.123' */ 
SELEC TO_CHAR(0.123) FROM DUAL

 上面的結果 '.123' 在大多數情況下都不是我們想要的結果,我們想要的應該是 '0.123'。

我們來看一下to_char函數的具體用法:

TO_CHAR ( n [, fmt [, 'nlsparam']] )
該函數將NUMBER類型的n按數值格式fmt轉換成VARCHAR2類型的值。'nlsparams'指定由數值格式的元素返回的字符,包括: 

.小數點字符 

.組分隔符 

.本地錢幣符號 

.國際錢幣符號 

變元的形式為: 

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

其中d為小數點字符,g為組分隔符。 

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

通過上面的了解,再查看fmt的一些格式,我們可以用以下表達式得到'0.123'的值:

/*0.123 ---> ' 0.123' */  
Select TO_CHAR(0.123,'0.999') FROM DUAL 
/*100.12 ---> '######' */  
Select TO_CHAR(100.12,'0.999') FROM DUAL 
/*1.12 ---> ' 1.120' */  
Select TO_CHAR(1.12,'0.999') FROM DUAL

 ' 0.123'是出來了,可是前面又多了一個空格。

對於 100.12 的值卻是######,以及'1.12'的值變成了 '1.120'。

我們重新確定一個新的需求:

1、去空格

2、小數點最多4位,最少保留2位。

    1--->'1.00';1.1--->'1.00';1.12-->'1.12';1.1234--->'1.1234';

    1.12345--->'1.1235'

最終實現如下:

/* 
  FM :除空格   
  9999999.0099:允許小數點左邊最大正數為7位,小數點右邊最少2位,最多4位,且在第5位進行四舍五入 
*/  
Select TO_CHAR(123.0233,'FM9999999.0099') FROM DUAL

to_char函數特殊用法 

to_char(sysdate,'d') 每周第幾天 
to_char(sysdate,'dd') 每月第幾天 
to_char(sysdate,'ddd') 每年第幾天 
to_char(sysdate,'ww') 每年第幾周 
to_char(sysdate,'mm') 每年第幾月 
to_char(sysdate,'q') 每年第幾季 
to_char(sysdate,'yyyy') 年 

比如要找某個時間為每周第幾天就可以 
SQL> select to_char(to_date('20070101','yyyymmdd'),'d') from dual;

 

 

轉載至:http://blog.csdn.net/aqszhuaihuai/article/details/4051401


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