[英]How to get end date based on a start date and duration (workdays) in PL/pgSQL?
我需要根據開始日期和持續時間( 表示工作日數的整數)計算作業的結束日期。
我已經根據這個答案編寫了一個函數,它計算兩個日期(開始和虛擬結束)之間的周末天數。
-- 0 Sunday
-- 1 Monday
-- 2 Tuesday
-- 3 Wednesday
-- 4 Thursday
-- 5 Friday
-- 6 Saturday
CREATE OR REPLACE FUNCTION weekend_days(date, date) RETURNS INT AS
$$
SELECT COUNT(days)::INT
FROM generate_series($1, $2, '1 day') AS days
WHERE EXTRACT(DOW FROM days) BETWEEN 1 AND 5;
$$
LANGUAGE 'sql' IMMUTABLE STRICT;
我想創建一個觸發器ON INSERT或ON UPDATE,它將填充相應的end_date
列。 顯然,將周末天數添加到給定的持續時間並不能解決問題。
有沒有辦法讓遞歸功能繼續添加周末或假期?
編輯:也許在這個答案中可以找到另一個很好的例子,那就是周末和假期。
CREATE OR REPLACE FUNCTION is_business_day(p_date date)
RETURNS boolean AS
$BODY$
DECLARE
is_business_day boolean;
dow int;
BEGIN
dow := extract('dow' from p_date);
IF dow = 6 OR dow = 0
THEN
is_business_day := FALSE;
ELSE
is_business_day := TRUE;
END IF;
RETURN is_business_day ;
END;
$BODY$
LANGUAGE plpgsql IMMUTABLE;
CREATE OR REPLACE FUNCTION working_date(date start_date, int duration)
RETURNS date AS
$BODY$
DECLARE
ret_date date;
loop_date date;
BEGIN
--add days
ret_date := start_date + (duration - 1);
loop_date := start_date + 1;
--add extra day for each no business day between start_date and ret_date
WHILE loop_date <= ret_date LOOP
IF not is_business_day(loop_date) THEN
ret_date := ret_date + 1;
END IF;
loop_date := loop_date + 1;
END LOOP;
--add day if ret_date is no business day
WHILE not is_business_day(ret_date) LOOP
ret_date := ret_date + 1;
END LOOP;
RETURN ret_date;
END;
$BODY$
LANGUAGE plpgsql VOLATILE SECURITY DEFINER
COST 100;
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