在 Oracle SQL 中手动计算年的周数

Question

我有一个日期列，并且我需要在 oracle 中计算他们一年中的周数的另一列，周应该是从星期日到星期六，从一年的第一天开始。

例如今年

Week 1 : 1 Jan 2020 (Wednesday) - 4 Jan 2020(Saturday)


Week 2 : 5 Jan 2020 (Sunday)        - 11 Jan 2020(Saturday)

. . . . .


Week 5 : 26 Jan 2020 (Sunday) - 1 Feb 2020 (Saturday)

等等...

Answer 1

您需要使用层次结构查询编写自己的逻辑。

类似于以下内容：

 SQL> SELECT WEEKNUMBER, 2 WEEK_START, 3 CASE WHEN WEEKNUMBER = 1 THEN FIRST_WEEKEND ELSE WEEK_START + 6 END AS WEEK_END 4 FROM 5 (SELECT 6 CASE 7 WHEN LEVEL = 1 THEN FIRST_DAY 8 ELSE FIRST_WEEKEND + ( LEVEL - 2 ) * 7 + 1 9 END AS WEEK_START, 10 FIRST_WEEKEND, 11 LEVEL AS WEEKNUMBER 12 FROM 13 ( SELECT 14 TRUNC(SYSDATE, 'YEAR') FIRST_DAY, 15 NEXT_DAY(TRUNC(SYSDATE, 'YEAR'), 'SATURDAY') FIRST_WEEKEND 16 FROM DUAL ) 17 CONNECT BY 18 CASE WHEN LEVEL = 1 THEN FIRST_DAY 19 ELSE FIRST_WEEKEND + ( LEVEL - 2 ) * 7 + 1 20 END < ADD_MONTHS(TRUNC(SYSDATE, 'YEAR'), 12)); WEEKNUMBER WEEK_STAR WEEK_END ---------- --------- --------- 1 01-JAN-20 04-JAN-20 2 05-JAN-20 11-JAN-20 3 12-JAN-20 18-JAN-20 4 19-JAN-20 25-JAN-20 5 26-JAN-20 01-FEB-20 6 02-FEB-20 08-FEB-20 7 09-FEB-20 15-FEB-20 8 16-FEB-20 22-FEB-20 9 23-FEB-20 29-FEB-20 10 01-MAR-20 07-MAR-20 11 08-MAR-20 14-MAR-20 ....... ....... 53 27-DEC-20 02-JAN-21

干杯！！

Answer 2

另一种选择是

with t as
(
 select trunc(sysdate,'yyyy')+level-1 as day, to_char(trunc(sysdate,'yyyy')+level-1,'DY','NLS_DATE_LANGUAGE=AMERICAN') as weekday, level - 1 as lvl
   from dual
 connect by level <= 366
), t1 as
(
select case
         when lvl = 0 then
          day
         else
          case
            when weekday = 'SUN' then
             day
          end
       end as day1,       
       lvl
  from t
), t2 as
(
select case
         when weekday = 'SAT' then
          day
       end as day2,
       lvl
  from t
)
select concat( 'Week ', wk1) as week, day1, day2  
  from 
  (
   select row_number() over (order by lvl) wk1, day1
     from t1 where day1 is not null ) t1 
  left join    
  (
   select row_number() over (order by lvl) wk2, day2
     from t2 where day2 is not null ) t2  
    on wk2 = wk1  

通过使用select .. from dual connect by level语法和case..when表达式来扫描所有当前年份。

演示