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函数to_char转化数字型指定小数点位数的用法
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'*/
Select TO_CHAR(1.0123) FROM DUAL
/*123--->'123'*/
Select TO_CHAR(123) FROM DUAL
接下来再看看下面：
/*0.123 ---> '.123' */
SELEC TO_CHAR(0.123) FROM DUAL
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
通过上面的了解，再查看fmt的一些格式，我们可以用以下表达式得到'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'是出来了，可是前面又多了一个空格。
对于 100.12 的值却是######，以及'1.12'的值变成了 '1.120'。
我们重新确定一个新的需求：
1、去空格
2、小数点最多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'
最终实现如下：
/*
FM ：除空格
9999999.0099：允许小数点左边最大正数为7位，小数点右边最少2位，最多4位，且在第5位进行四舍五入
*/
Select TO_CHAR(123.0233,'FM9999999.0099') FROM DUAL