sql日期函数

Question

我有一个'date1'字段值从01/01/1960开始到2014年9月14日。我有一群这一领域进入

从今天开始组最后两个月到

'1' (sept 2014, aug 2014) 
(july 2014, june 2014) to '2' 
(may 2014, apr 2014) to '3' 
(mar 2014, feb 2014) to '4' 
(jan 2014, dec 2013) to '5' 
(nov 2013,oct 2013) to '6' 
(<=sept 2013) to '7' 

如何对数据进行分组？

Answer 1

一个简单的，冗长的和静态的解决方案是这样的：

WITH t1 AS 
(
    SELECT CASE WHEN date1 >= TO_DATE('1-AUG-2014') AND date1 < TO_DATE('1-OCT-2014') THEN 1 ELSE 
      CASE WHEN date1 >= TO_DATE('1-JUN-2014') AND date1 < TO_DATE('1-AUG-2014') THEN 2 ELSE 
      ... etc. END AS dategroup, 
      othercolumns 
    FROM Table1 
) 
SELECT dategroup FROM t1 
GROUP BY dategroup;