Oracle 中 TO_CHAR用法

（1）用作日期转换：

to_char(date,'格式');

select to_date('2005-01-01 ','yyyy-MM-dd') from dual;
select to_char(sysdate,'yyyy-MM-dd HH24:mi:ss') from dual;

（2）处理数字：

to_char(number,'格式');

select to_char(88877) from dual;
select to_char(1234567890,'099999999999999')  from dual;
select to_char(12345678,'999,999,999,999')  from dual;
select to_char(123456,'99.999')  from dual;
select to_char(1234567890,'999,999,999,999.9999')  from dual;

（3）to_char(salary,'$99,99');

 select TO_CHAR(123,'$99,999.9') from dual;

（4）用于进制转换：将10进制转换为16进制；

select to_char(4567,'xxxx') from dual;
select to_char(123,'xxx') from dual;

//// to_char 例子
①其9代表：如果存在数字则显示数字，不存在则显示空格
②其0代表：如果存在数字则显示数字，不存在则显示0，即占位符。
③其FM代表：删除如果是因9带来的空格，则删除之
to_char(now(),'Day, HH12:MI:SS') 'Tuesday , 05:39:18'
to_char(now(),'FMDay, HH12:MI:SS') 'Tuesday, 05:39:18'
to_char(-0.1,'99.99') ' -.10'
to_char(-0.1,'FM9.99') '-.1'
to_char(0.1,'0.9') ' 0.1'
to_char(12,'9990999.9') ' 0012.0'
to_char(12,'FM9990999.9') '0012'
to_char(485,'999') ' 485'
to_char(-485,'999') '-485'
to_char(485,'9 9 9') ' 4 8 5'
to_char(1485,'9,999') ' 1,485'
to_char(1485,'9G999') ' 1 485'
to_char(148.5,'999.999') ' 148.500'
to_char(148.5,'999D999') ' 148,500'
to_char(3148.5,'9G999D999') ' 3 148,500'
to_char(-485,'999S') '485-'
to_char(-485,'999MI') '485-'
to_char(485,'999MI') '485'
to_char(485,'PL999') '+485'
to_char(485,'SG999') '+485'
to_char(-485,'SG999') '-485'
to_char(-485,'9SG99') '4-85'
to_char(-485,'999PR') '<485>'
to_char(485,'L999') 'DM 485
to_char(485,'RN') ' CDLXXXV'
to_char(485,'FMRN') 'CDLXXXV'
to_char(5.2,'FMRN') V
to_char(482,'999th') ' 482nd'
to_char(485, '"Good number:"999') 'Good number: 485'
to_char(485.8,'"Pre-decimal:"999" Post-decimal:" .999') 'Pre-decimal: 485 Post-decimal: .800'
to_char(12,'99V999') ' 12000'
to_char(12.4,'99V999') ' 12400'
to_char(12.45, '99V9') ' 125'

Oralce 中TO_CHAR( 日期型值 ， 格式参数)  用法

Oracle 中 TO_CHAR 函数用法如下列表

例：

select trunc(sysdate,'IW') from dual; 本周第一天
select trunc(sysdate,'yy') from dual ; 本年第一天
select trunc(sysdate,'mm') from dual; 本月第一天
select trunc(sysdate,'day')+1 from dual; 本周第一天
select to_char(SYSTIMESTAMP,'dd-mon-yy HH12:MI:SS.FF4 AM') from dual;
select TO_char(TO_TIMESTAMP('30-11月-10 02:20:00.7490 下午','dd-mon-yy HH12:MI:SS.FF4 AM'),'YYYY/MM/DD HH24:MI:SS') from DUAL;