oracle TO_CHAR()常规用法

1.用作日期转换

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

2.处理数字

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,'9999999.999') from dual

select to_char(1234567890,'999,999,999,999.9999') from dual

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

3.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

 4.to_char说明

其9代表：如果存在数字则显示数字，不存在则显示空格
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。
其FM代表：删除如果是因9带来的空格，则删除之
select to_char(sysdate,'FMDay,HH24:MI:SS') from dual

select to_char(12,'9990999.9') from dual

 select to_char(12,'FM9990999.9') from dual

5.Oralce中 to_char(日期型值,格式参数)用法