Oracle 获取当前日期及日期格式

<wbr><wbr> 获取系统日期：<wbr><wbr><span style="padding:0px; margin:0px; color:rgb(255,0,0)">SYSDATE()<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></span><wbr><wbr> 格式化日期：<wbr><wbr><wbr><wbr><wbr><span style="padding:0px; margin:0px; color:rgb(255,0,0)">TO_CHAR(SYSDATE(),'YY/MM/DD HH24:MI:SS)<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></span><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>或<wbr><span style="padding:0px; margin:0px; color:rgb(255,0,0)">TO_DATE(SYSDATE(),'YY/MM/DD HH24:MI:SS)<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></span><wbr><wbr> 格式化数字：<wbr><wbr><wbr><wbr><wbr><wbr><span style="padding:0px; margin:0px; color:rgb(255,0,0)">TO_NUMBER</span></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> 注： TO_CHAR<wbr> 把日期或数字转换为字符串<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> TO_CHAR(number, '格式')<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>TO_CHAR(salary, '$99,999.99')<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> TO_CHAR(date, '格式')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> TO_DATE<wbr> 把字符串转换为数据库中的日期类型<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> TO_DATE(char, '格式')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> TO_NUMBER<wbr> 将字符串转换为数字<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>TO_NUMBER(char, '格式')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

返回系统日期,输出 25-12月-09
select sysdate from dual;
mi是分钟，输出 2009-12-25 14:23:31
select to_char(sysdate,'yyyy-MM-dd HH24:mi:ss') from dual;
mm会显示月份，输出 2009-12-25 14:12:31<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select to_char(sysdate,'yyyy-MM-dd HH24:<span style="padding:0px; margin:0px; color:rgb(255,0,0)">mm</span>:ss') from dual;</span><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"> 输出 09-12-25 14:23:31<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select to_char(sysdate,'yy-mm-dd hh24:mi:ss') from dual<wbr><wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></wbr></wbr></span>输出 2009-12-25 14:23:31</wbr>

select to_date('2009-12-25 14:23:31','yyyy-mm-dd,hh24:mi:ss') from dual<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></wbr>而如果把上式写作：
<wbr>select to_date('2009-12-25 14:23:31','yyyy-mm-dd,<span style="padding:0px; margin:0px; color:rgb(255,0,0)">hh</span>:mi:ss') from dual</wbr>
则会报错，因为小时hh是12进制，14为非法输入，不能匹配。

输出 $10,000,00 ：
select to_char(1000000,'$99,999,99') from dual;
输出 RMB10,000,00 ：<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select to_char(1000000,'L99,999,99') from dual;</span><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"> 输出 1000000.12 ：<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select trunc(to_number('1000000.123'),2) from dual;<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></span><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select to_number('1000000.123') from dual;</span></wbr>

转换的格式：

表示 year 的：y 表示年的最后一位 、
<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> yy 表示年的最后2位 、<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> yyy 表示年的最后3位 、<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> yyyy 用4位数表示年</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

表示month的： mm 用2位数字表示月 、
<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> mon 用简写形式， 比如11月或者nov 、<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>month 用全称， 比如11月或者november</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

表示day的：dd<wbr> 表示当月第几天 、<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>ddd 表示当年第几天 、<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> dy<wbr> 当周第几天，简写， 比如星期五或者fri 、<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>day 当周第几天，全称， 比如星期五或者friday</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

表示hour的：hh<wbr><wbr> 2位数表示小时 12进制、<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> hh24 2位数表示小时 24小时</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

表示minute的：mi 2位数表示分钟

表示second的：ss 2位数表示秒 60进制

表示季度的：q 一位数 表示季度 （1-4）

另外还有ww 用来表示当年第几周 w用来表示当月第几周。

24小时制下的时间范围：00：00：00-23：59：59
12小时制下的时间范围：1：00：00-12：59：59

数字格式:<wbr> 9<wbr> 代表一个数字<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> 0<wbr> 强制显示0<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> $<wbr> 放置一个$符<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> L<wbr> 放置一个浮动本地货币符<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>.<wbr> 显示小数点<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>,<wbr> 显示千位指示符</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

补充：
当前时间减去7分钟的时间<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate,sysdate - interval '7' MINUTE from dual;</span><wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"> 当前时间减去7小时的时间<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate - interval '7' hour from dual<span style="padding:0px; margin:0px">;</span></span><wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"> 当前时间减去7天的时间<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate - interval '7' day from dual;</span><wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"> 当前时间减去7月的时间<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate,sysdate - interval '7' month from dual;<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></wbr></span>当前时间减去7年的时间<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate,sysdate - interval '7' year from dual;<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"></wbr></span>时间间隔乘以一个数字<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><span style="padding:0px; margin:0px; color:rgb(0,0,255)">select sysdate,sysdate - 8*interval '7' hour from dual;</span></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

含义解释：<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr> Dual伪列<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> Dual 是 Oracle中的一个实际存在的表，任何用户均可读取，常用在没有目标表的select语句块中。<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> 不同系统可能返回日期的格式不一样。<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> 返回当前连接的用户：select user from dual;</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>