Oracle 獲取當前日期及日期格式

<wbr><wbr> 獲取系統日期：<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> 格式化數字：<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> 把日期或數字轉換為字符串<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> 把字符串轉換為數據庫中的日期類型<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> 將字符串轉換為數字<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>

返回系統日期,輸出 25-12月-09
select sysdate from dual;
mi是分鐘，輸出 2009-12-25 14:23:31
select to_char(sysdate,'yyyy-MM-dd HH24:mi:ss') from dual;
mm會顯示月份，輸出 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"> 輸出 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>輸出 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>而如果把上式寫作：
<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>
則會報錯，因為小時hh是12進制，14為非法輸入，不能匹配。

輸出 $10,000,00 ：
select to_char(1000000,'$99,999,99') from dual;
輸出 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"> 輸出 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>

轉換的格式：

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位數表示年</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位數字表示月 、
<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr> mon 用簡寫形式， 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 用全稱， 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> 表示當月第幾天 、<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 表示當年第幾天 、<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> 當周第幾天，簡寫， 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 當周第幾天，全稱， 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位數表示小時 12進制、<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位數表示小時 24小時</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位數表示分鐘

表示second的：ss 2位數表示秒 60進制

表示季度的：q 一位數 表示季度 （1-4）

另外還有ww 用來表示當年第幾周 w用來表示當月第幾周。

24小時制下的時間范圍：00：00：00-23：59：59
12小時制下的時間范圍：1：00：00-12：59：59

數字格式:<wbr> 9<wbr> 代表一個數字<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> 強制顯示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> $<wbr> 放置一個$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> 放置一個浮動本地貨幣符<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> 顯示小數點<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> 顯示千位指示符</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>

補充：
當前時間減去7分鐘的時間<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"> 當前時間減去7小時的時間<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"> 當前時間減去7天的時間<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"> 當前時間減去7月的時間<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>當前時間減去7年的時間<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>時間間隔乘以一個數字<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>

含義解釋：<wbr><br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr> Dual偽列<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> Dual 是 Oracle中的一個實際存在的表，任何用戶均可讀取，常用在沒有目標表的select語句塊中。<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> 不同系統可能返回日期的格式不一樣。<br style="padding-bottom:0px; padding-top:0px; padding-left:0px; margin:0px; padding-right:0px"><wbr><wbr><wbr><wbr><wbr> 返回當前連接的用戶：select user from dual;</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>