How to get number of working days in Informix between two dates

问题

I need to create function in Informix that calculates number of working days in between two given dates. I have created table "prazkal" with holidays, and two Informix functions:

create function is_holiday(d datetime year to day)
returning boolean;
    define hcnt integer;

    if weekday(d) = 0 or weekday(d) = 6 then
        return 't';
    end if;

    ---code that check if 'd' is marked as holiday in calendar
    select count(*) into hcnt from prazkal where datpra = d;
    if hcnt > 0 then
      return 't';
    end if;

    return 'f';
end function;

create function work_days(start_d DATE, end_d DATE)
returning integer;
define new_d datetime year to day;
define count_days integer;
define i integer;
    let i = 0;

    let count_days = end_d - start_d;
    let new_d = CAST(end_d AS DATETIME YEAR TO DAY);


    while i < count_days
        let new_d = new_d - interval(1) day to day;
        if not is_holiday(new_d) then
            let i = i + 1;
        end if;
    end while


    return i;
end function;

Both of my functions are modified from this post. Result of function work_days is number of days between two dates (end_d, start_d), and not number of working days. Where did I made error?

回答1:

Your loop increments i until it is the number in count_days, so the answer will always be count_days (calculated very slowly). You need a second condition new_d > start_d too:

while i < count_days and new_d > start_d
    let new_d = new_d - interval(1) day to day;
    if not is_holiday(new_d) then
        let i = i + 1;
    end if;
end while

The > is appropriate since the loop decrements and then checks new_d, so the last cycle tests start_d.

来源：https://stackoverflow.com/questions/29748645/how-to-get-number-of-working-days-in-informix-between-two-dates

标签

sql

informix