在SQL中将日期与一年中的季节分开的问题

Question

我的DW中有一个TIME维度,我想添加一个阵营来填补今年的赛季.我想做这样的事情:

create or replace
PROCEDURE "PROC_UPDATE_SEASON" 

IS 
CURSOR curs IS   
SELECT * FROM indw.time FOR UPDATE;  
 cur_d NUMBER;   
 cur_m NUMBER;   
 start_d NUMBER;   
 start_m NUMBER;   
 end_d NUMBER;   
 end_m NUMBER;
 cur_Date DATE;     

 BEGIN 
 FOR cs IN curs 
 LOOP 
     cur_d := to_number(to_char(cs.time_DAY,'dd')); 
     cur_m := to_number(to_char(cs.time_DAY,'mm')); 
     cur_date:= cs.time_DAY; -- this is my date dd-mm-yyyy or dd/mm/yyyy


     if ((cur_date in format dd/mm is >= 21/12 and <=31/12) OR cur_date>=01/01 and <=20/03) 
     UPDATE time t set t.time_SEASON = 'Winter' WHERE CURRENT OF curs; 
     else if cur_date_in format dd/mm is between a date and another then it's Spring)
       -- and so on ... 
     END LOOP; 
 END;

有没有办法使用to_char和to_date来实现这一目标？我正在尝试,但总是得到错误:(分别比较月份和日期将是一个巨大的,IMO,愚蠢的工作.

你能给我一些提示吗？

我真的只使用像dd/mm <= another_date_with_only_day_and_month这样的东西

Answer 1

不需要游标和循环:

update indw.time
set t.time_SEASON = case
                      when to_char(time_DAY,'MMDD') between '1221' and '1231' 
                        or to_char(time_DAY,'MMDD') between '0101' and '0320' 
                         then 'Winter'
                      when ...
                    end 

更妙的是,在Oracle 11g中,你可以在虚拟列添加到基于该CASE表达式表格,使得每一行自动拥有正确的time_season无需进行更新.