Sql：两个日期之间的差异

Question

一个简短的问题：

我正在使用此代码

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

计算两个日期之间的差异。

我想补充一点，它忽略了星期六，星期日和节假日（不是学校假期，我的意思是假期，如圣诞节，东方......）。 我当地的时区是德国（每个国家都有自己的假期）。

感谢帮助！

Answer 1

获取星期六和星期日的天数并不是那么困难，你会在SO找到几个解决方案。

考虑到假期更具挑战性。 一种解决方案是使用Oracle SCHEDULER 。 默认情况下，这用于SCHEDULER JOBS ，但我没有看到任何不将其用于其他目的的原因。

最大的问题是复活节，请看这里： Computus 。 我认为最有效的方法是硬编码日期并手动维护它们。

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;
/

请参阅此处的日历语法 ： Calendaring Syntax

然后你可以使用这样的时间表：

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;

输出接下来的20个holiays进行测试：

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

我甚至发现了一个更紧凑的版本：

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;