oracle转char类型转换,Oracle的数据类型转换to_char（date）Oracle的数据类型转换
Oracle的数据类型转换分为显式数据类型转换和隐式类型转换
在⼀般状况下，隐式数据类型转换是可⽤的，但建议你作显⽰数据类型转换以确保SQL的可靠性.
显式的数据类型转换包括:
to_number 字符转换为数字
to_date 字符转换为⽇期
to_char 数字转化为字符
to_char ⽇期转化为字符
TO_CHAR(date,'format_model')
必须加单引号,⽽且区分⼤⼩写
可以包含任⼀有效的⽇期格式元素
有⼀个fm元素⽤来删除填补的空，或者前导零
⽤⼀个逗号与⽇期值分开
select employee_id,to_char(hire_date,'MM/YY') as month
from employees
where last_name='Higgins'
employee_id month
205 06/94
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss am') as today from dual
2006-06-24 13:39:06 下午
select to_char(to_date('21-1⽉-95'),'yyyy-mm-dd hh24:mi:ss am') as today from dual
1995-01-21 00:00:00 上午
select to_char(sysdate,'dd "of" month') from dual
24 of 6⽉
select to_char(syadate,'yyyy-mm-dd cc') from dual
2006-06-24 21
cc：世纪
select to_char(sysdate,'yyy-mm-dd cc') as today from dual
006-06-24 21
select to_char(sysdate,'yy-mm-dd cc') as today from dual
06-06-24 21
select to_char(sysdate,'y,yyy-mm-dd cc') as today from dual
2,006-06-24 21
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.javascript
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
oracle四舍五入Seconds past midnight (0-86399).
FF
Fractional seconds.
The following are date examples for the to_char function.html
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.java
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".git
Oracle函数to_char转化数字型指定⼩数点位数的⽤法数据库
to_char，函数功能，就是将数值型或者⽇期型转化为字符型。函数
好⽐最简单的应⽤：post
Select
TO_CHAR(1.0123)
FROM
DUAL
Select
TO_CHAR(123)
FROM
DUAL
接下来再看看下⾯：this
SELEC
TO_CHAR(0.123)
FROM
DUAL
上⾯的结果 '.123' 在⼤多数状况下都不是咱们想要的结果，咱们想要的应该是 '0.123'。url
咱们来看⼀下to_char函数的具体⽤法：spa
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
经过上⾯的了解，再查看fmt的⼀些格式，咱们能够⽤如下表达式获得'0.123'的值：
Select
TO_CHAR(0.123,
'0.999')
FROM
DUAL
Select
TO_CHAR(100.12,
'0.999')
FROM
DUAL
Select
TO_CHAR(1.12,
'0.999')

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