SQL：兩個日期

Question

一個簡短的問題區別：

我使用此代碼

SELECT trunc (SYSDATE) - TO_DATE('04/10/2015','mm/dd/yyyy') Differenz FROM DUAL; 

計算兩個日期之間的差異性。

我想補充一點，它忽略了週六，週日和節假日（不是學校假期，我的意思是假期像聖誕節，東部..）。我當地的時區是德國（每個國家都有自己的假期）。

感謝您的幫助！

Answer 1

排除星期六和星期日的天數並不困難，您會在SO上找到幾種解決方案。

考慮假期更具挑戰性。一種解決方案是使用Oracle SCHEDULER。默認情況下，這用於SCHEDULER JOBS，但我沒有看到任何理由不將它用於其他目的。

最大的問題是復活節，看到這裏：Computus。 我認爲最有效的方法是硬編碼日期並手動維護它們。

BEGIN 
    DBMS_SCHEDULER.CREATE_SCHEDULE('New_Year', repeat_interval => 'FREQ=YEARLY;BYDATE=0101'); 

    DBMS_SCHEDULER.CREATE_SCHEDULE('Easter_Sunday', repeat_interval => 'FREQ=YEARLY;BYDATE=20150405, 20160327, 20170416, 20170416, 20180401, 20190421, 20200412', comments => 'Hard coded till 2020'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Good_Friday', repeat_interval => 'FREQ=YEARLY;BYDATE=20150405-2D, 20160327-2D, 20170416-2D, 20170416-2D, 20180401-2D, 20190421-2D, 20200412-2D'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Easter_Monday', repeat_interval => 'FREQ=YEARLY;BYDATE=20150405+1D, 20160327+1D, 20170416+1D, 20170416+1D, 20180401+1D, 20190421+1D, 20200412+1D'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Ascension_Day', repeat_interval => 'FREQ=YEARLY;BYDATE=20150405+39D,20160327+39D,20170416+39D,20170416+39D,20180401+39D,20190421+39D,20200412+39D'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Pentecost_Monday', repeat_interval => 'FREQ=YEARLY;BYDATE=20150405+50D,20160327+50D,20170416+50D,20170416+50D,20180401+50D,20190421+50D,20200412+50D'); 

    DBMS_SCHEDULER.CREATE_SCHEDULE('Repentance_and_Prayer', repeat_interval => 'FREQ=DAILY;BYDATE=1122-SPAN:7D;BYDAY=WED', 
     comments => 'Wednesday before November 23th, Buss- und Bettag'); 
    -- alternative solution: 
    --DBMS_SCHEDULER.CREATE_SCHEDULE('Repentance_and_Prayer', repeat_interval => 'FREQ=MONTHLY;BYMONTH=NOV;BYDAY=3 WED', 
    -- comments => '3rd Wednesday in November'); 

    DBMS_SCHEDULER.CREATE_SCHEDULE('Labor_Day', repeat_interval => 'FREQ=YEARLY;BYDATE=0501'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('German_Unity_Day', repeat_interval => 'FREQ=YEARLY;BYDATE=1003'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Christmas', repeat_interval => 'FREQ=YEARLY;BYDATE=1225+SPAN:2D'); 

    DBMS_SCHEDULER.CREATE_SCHEDULE('Christian_Celebration_Days', repeat_interval => 'FREQ=DAILY;INTERSECT=Easter_Sunday,Good_Friday,Easter_Monday,Ascension_Day,Pentecost_Monday,Repentance_and_Prayer,Christmas'); 
    -- alternative solution: 
    -- DBMS_SCHEDULER.CREATE_SCHEDULE('Christian_Celebration_Days', repeat_interval => 'FREQ=Good_Friday;BYDAY=1 MON, 6 THU,8 MON'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('Political_Holidays', repeat_interval => 'FREQ=DAILY;INTERSECT=New_Year,Labor_Day,German_Unity_Day'); 


END; 
/

日曆看到這裏的語法：Calendaring Syntax

然後你可以使用時間表是這樣的：

CREATE OR REPLACE FUNCTION DateDiff(end_date IN TIMESTAMP) RETURN INTEGER AS 
    next_run_date TIMESTAMP := TRUNC(SYSTIMESTAMP); 
    res INTEGER := 0; 
BEGIN 
    IF end_date > SYSTIMESTAMP THEN 
     LOOP 
      DBMS_SCHEDULER.EVALUATE_CALENDAR_STRING('FREQ=DAILY;INTERVAL=1;BYDAY=MON,TUE,WED,THU,FRI; EXCLUDE=Christian_Celebration_Days,Political_Holidays', NULL, next_run_date, next_run_date); 
      EXIT WHEN next_run_date >= end_date; 
      res := res + 1; 
     END LOOP; 
     RETURN res; 
    ELSE 
     RAISE VALUE_ERROR; 
    END IF;  
END; 

SELECT DateDiff(TO_DATE('04/10/2015','mm/dd/yyyy')) AS Differenz FROM DUAL; 

輸出未來20個holiays來進行測試：

DECLARE 
    next_run_date TIMESTAMP; 
BEGIN 
    FOR i IN 1..20 LOOP 
     DBMS_SCHEDULER.EVALUATE_CALENDAR_STRING('FREQ=DAILY;INTERSECT='Christian_Celebration_Days,Political_Holidays', NULL, next_run_date, next_run_date); 
     DBMS_OUTPUT.PUT_LINE(next_run_date); 
    END LOOP; 
END; 

更新

我甚至發現了一個更緊湊的版本：

BEGIN 
    -- Start with first celebration day (good Friday), all dependent celebration days have to be after this day for proper calculation of schedule 
    DBMS_SCHEDULER.CREATE_SCHEDULE('GOOD_FRIDAY', repeat_interval => 'FREQ=YEARLY;BYDATE=20100402,20110422,20120406,20130329,20140418,20150403,20160325,20170414,20180330,20190419,20200410,20210402,20220410,20230407,20240329,20250418,20260403,20270326,20280414,20290330,20300419', comments => 'Hard coded 2010 to 2030'); 
    -- Easter Sunday can be skipped for list of holidays, otherwise 'FREQ=Good_Friday;BYDAY=1 SUN+SPAN:2D' 
    DBMS_SCHEDULER.CREATE_SCHEDULE('EASTER_MONDAY', repeat_interval => 'FREQ=Good_Friday;BYDAY=1 MON', comments => '1st Monday after Good Friday' 
    DBMS_SCHEDULER.CREATE_SCHEDULE('ASCENSION_DAY', repeat_interval => 'FREQ=Good_Friday;BYDAY=6 THU', comments => '6th Thursday after Good Friday (40 days after Easter)'); 
    -- Pentecost Sunday can be skipped for list of holidays, otherwise 'FREQ=Good_Friday;BYDAY=8 SUN+SPAN:2D' 
    DBMS_SCHEDULER.CREATE_SCHEDULE('PENTECOST_MONDAY', repeat_interval => 'FREQ=Good_Friday;BYDAY=8 MON', comments => '8th Monday after Good Friday (50 days after Easter)'); 
    DBMS_SCHEDULER.CREATE_SCHEDULE('EASTER_RELATED_DAYS', repeat_interval => 'FREQ=Good_Friday;BYDAY=1 MON, 6 THU,8 MON' 
END;