oracle:如何用sql生成日历

BI分析中，经常需要将事实表与时间维度表关联起来，按年/月/日来逐层展示，常用的做法是创建一张日历表，结构类似如下：

create table T_BAS_CALENDAR

(

  d_year  NUMBER(4) not null,

  d_month NUMBER(2) not null,

  d_day   NUMBER(2) not null

);

comment on table T_BAS_CALENDAR

  is '日历表';

comment on column T_BAS_CALENDAR.d_year

  is '年';

comment on column T_BAS_CALENDAR.d_month

  is '月';

comment on column T_BAS_CALENDAR.d_day

  is '日';

alter table T_BAS_CALENDAR

  add constraint PK_BAS_CALENDAR primary key (D_YEAR, D_MONTH, D_DAY);

但是如何向这张表批量插入日历数据，方法就很多了，下面是仅用SQL语言生成日历的参考方法：

 1 create or replace procedure P_IMPORT_CALENDAR(p_year_start number,

 2                                               p_year_end   number) is

 3   cmonth    integer;

 4   cyear     integer;

 5   cday      integer;

 6   day_first integer;

 7   day_last  integer;

 8 begin

 9   --生成从p_year_start到p_year_end的所有日历 created by [email protected] 2015-04-27

10   

11   --firstly,delete history records

12   delete from T_BAS_CALENDAR where d_year between p_year_start and p_year_end;

13   for cyear in p_year_start .. p_year_end loop

14     for cmonth in 1 .. 12 loop

15       --get first-day of Month

16       select to_number(cyear || lpad(cmonth, 2, '0') || '01', '99999999')

17         into day_first

18         from dual;

19       --last-day of Month

20       select to_number(to_char(add_months(to_date(day_first, 'yyyyMMdd'), 1) - 1,

21                                'yyyyMMdd'),

22                        '99999999')

23         into day_last

24         from dual;

25       for cday in day_first .. day_last loop   

26         --insert to table  

27         INSERT INTO T_BAS_CALENDAR

28           (D_YEAR, D_MONTH, D_DAY)

29         VALUES

30           (CYEAR, CMONTH, SUBSTR(cday, 7));

31       end loop;

32     end loop;

33   end loop;

34   commit;

35 end P_IMPORT_CALENDAR;