Oracle 日历
此方法只是用于Oracle数据库。
直接看例子吧：
select ceil((cdate+(to_char(to_date('20100101','yyyymmdd'),'d'))-2)/7) as week,
sum(decode(to_char(everyday,'d'),'2',to_char(everyday,'dd'))) as 星期一,
sum(decode(to_char(everyday,'d'),'3',to_char(everyday,'dd'))) as 星期二,
sum(decode(to_char(everyday,'d'),'4',to_char(everyday,'dd'))) as 星期三,
sum(decode(to_char(everyday,'d'),'5',to_char(everyday,'dd'))) as 星期四,
sum(decode(to_char(everyday,'d'),'6',to_char(everyday,'dd'))) as 星期五,
sum(decode(to_char(everyday,'d'),'7',to_char(everyday,'dd'))) as 星期六,
sum(decode(to_char(everyday,'d'),'1',to_char(everyday,'dd'))) as 星期日
from(
select everyday,everyday-TO_DATE('20100101','YYYYMMDD')+1 as cdate,decode(to_char(everyday,'d'),1,7,to_char(everyday,'d')-1) as sweek
from(
SELECT NEXT_DAY(TO_DATE('20100101','YYYYMMDD'),2)-7+LEVEL-1 AS everyday FROM DUAL CONNECT BY LEVEL <=(TRUNC(NEXT_DAY(LAST_DAY(TO_DATE('20100101','YYYYMMDD')),2))-(TRUNC(NEXT_DAY(TO_DATE('20100101','YYYYMMDD'),2))-7))
)
)group by ceil((cdate+(to_char(to_date('20100101','yyyymmdd'),'d'))-2)/7) order by 1
结果---------------------------------------------------------------------------------------------------------------------------
如果不需要 本月前后的日期，即 上个月的 28，29，30，31号
只需修改以上代码就可以，当然也可以更简单，如下
select ceil((to_char(everyday,'dd')+(to_char(to_date('20100101','yyyymmdd'),'d'))-2)/7) as week,
sum(decode(to_char(everyday,'d'),'2',to_char(everyday,'dd'))) as 星期一,
sum(decode(to_char(everyday,'d'),'3',to_char(everyday,'dd'))) as 星期二,
sum(decode(to_char(everyday,'d'),'4',to_char(everyday,'dd'))) as 星期三,
sum(decode(to_char(everyday,'d'),'5',to_char(everyday,'dd'))) as 星期四,
sum(decode(to_char(everyday,'d'),'6',to_char(everyday,'dd'))) as 星期五,
sum(decode(to_char(everyday,'d'),'7',to_char(everyday,'dd'))) as 星期六,
sum(decode(to_char(everyday,'d'),'1',to_char(everyday,'dd'))) as 星期日
from(select everyDay,decode(to_char(everyDay,'d'),1,7,to_char(everyDay,'d')-1) as sweek from( select to_date('20100101','yyyymmdd') + level - 1 as everyDay
from dual connect by level <= (last_day(to_date('20100101','yyyymmdd')) - to_date('20100101','yyyymmdd') +1))
)
group by ceil((to_char(everyday,'dd')+(to_char(to_date('20100101','yyyymmdd'),'d'))-2)/7) order by 1;
结果下：-----------------------------------------------------------------------------------------------------------------------
PS：年历的实现方式
只需要修改 红色部分代码中的日期既可以实现，我在这里不贴出效果图了，当然oracle也提供了年历的代码，
不过是以周日作为一周的第一天，oracle代码如下：
select case
when (new_yweek = min(new_yweek)over(partition by mon order by new_yweek)) then
mon_name
else
null
end as month,
new_yweek as yweek,
row_number() over(partition by mon order by new_yweek) as mweek,
sum(decode(wday, '1', mday, null)) as sun,
sum(decode(wday, '2', mday, null)) as mon,
sum(decode(wday, '3', mday, null)) as tue,
sum(decode(wday, '4', mday, null)) as wed,
sum(decode(wday, '5', mday, null)) as thu,
sum(decode(wday, '6', mday, null)) as fri,
sum(decode(wday, '7', mday, null)) as sat
from (select dayofyear as everyday,
to_char(dayofyear, 'mm') as mon,
to_char(dayofyear, 'Month') as mon_name,
to_char(dayofyear, 'w') as mweek,
to_char(dayofyear, 'ww') as yweek,
case
when (to_char(to_date(:year || '0101', 'yyyymmdd'), 'd') > '1') and
(to_char(dayofyear, 'd') <
to_char(to_date(:year || '0101', 'yyyymmdd'), 'd')) then
to_char(to_char(dayofyear, 'ww') + 1, 'fm00')
else
to_char(dayofyear, 'ww')
end as new_yweek,
to_char(dayofyear, 'd') as wday,
to_char(dayofyear, 'dd') as mday
from (select to_date(:year || '0101', 'yyyymmdd') + level - 1 as dayofyear
from dual
connect by level <= to_char(to_date(:year || '0131', 'yyyymmdd'),'ddd')
)
)
group by mon, mon_name, new_yweek
下面是一个生成全年日历的例子
样式如下：
DT YR MM DD DAYOFWEEK WE Q BO ID
---------- ---- -- -- ------------ -- - -- --
2019-01-01 2019 01 01 星期二 01 1 01
2019-01-02 2019 01 02 星期三 01 1 01
2019-01-03 2019 01 03 星期四 01 1 01
2019-01-04 2019 01 04 星期五 01 1 01
2019-01-05 2019 01 05 星期六 01 1 01
2019-01-06 2019 01 06 星期日 01 1 01
2019-01-07 2019 01 07 星期一 01 1 02
2019-01-08 2019 01 08 星期二 02 1 02
2019-01-09 2019 01 09 星期三 02 1 02
2019-01-10 2019 01 10 星期四 02 1 02
2019-01-11 2019 01 11 星期五 02 1 02
代码如下：
select to_char(everyDay,'yyyy-mm-dd') as dt,
to_char(everyday,'yyyy') as yr,
to_char(everyday,'mm') as mm,
to_char(everyday,'dd') as dd,
to_char(everyday,'dy') as dayofweek,
/*ORACLE自定义的标准周*/
to_char(everyday,'WW') as weeknum,
/*该月的第几周*/
/*lpad(to_char(everyday,'w'),6) as monthOfWeek,*/
to_char(everyday,'Q') as qr,
/*ISO的标准周，通常使用这个*/
to_char(everyday,'IW') as bourse_week,
null as id
from(select trunc(sysdate, 'YYYY') + level - 1 as everyDay from dual
connect by level <=
(add_months(trunc(sysdate,'YYYY'),12)-1 - trunc(sysdate, 'YYYY') +1));
只要稍微变换一下，就可以实现很多种需求，有兴趣的朋友可以自己试一下。