Next Date Row with Value 1 in Teradata - teradata

Question

I need the the below output on Teradata :
DATE_HOME WORKING_DAY
01/01/2018 0
02/01/2018 1
03/01/2018 1
04/01/2018 1
05/01/2018 1
06/01/2018 0
07/01/2018 0
08/01/2018 1
09/01/2018 1
Output required
DATE_HOME WORKING_DAY Updated_DATE
01/01/2018 0 02/01/2018
02/01/2018 1 02/01/2018
03/01/2018 1 03/01/2018
04/01/2018 1 04/01/2018
05/01/2018 1 05/01/2018
06/01/2018 0 08/01/2018
07/01/2018 0 08/01/2018
08/01/2018 1 08/01/2018
09/01/2018 1 09/01/2018

Answer 1

That's a simple task for first_value:
first_value(case when WORKING_DAY = 1 then DATE_HOME end ignore nulls)
over (order by DATE_HOME
rows between current date and unbounded following)
Change the non-business dates into NULL and then search for the first non-NULL value.
Edit:
In fact there's no need for first_value as you sort by the same column, a simple min works, too:
min(case when WORKING_DAY = 1 then DATE_HOME end)
over (order by DATE_HOME
rows between current date and unbounded following)

Answer 2

Good lord, this is ugly, but it seems to work. I don't have access to a TD system, so it's more verbose than it could be:
SELECT
date_home,
working_day,
CAST(
CASE
-- If current date is a non-work day, add appropriate number of days to non-work day to get next work-day
WHEN working_day = 0 THEN date_home + INTERVAL '1' DAY * (ROW_NUMBER() OVER(PARTITION BY update_date ORDER BY date_home DESC))
ELSE date_home
END
AS DATE) AS Update_date
FROM (
SELECT
date_home,
working_day,
CASE
-- If current and previous days were non-work days, group row by PrevWorkDay value
WHEN MIN(working_day) OVER(ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) = 0 AND working_day = 0 THEN MIN(PrevWorkDay) OVER(ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING)
ELSE PrevWorkDay
END AS Update_Date
FROM (
SELECT
date_home,
working_day,
CASE
-- Track "baseline" previous date_home value for new group of "non-work day" rows
WHEN COALESCE(MIN(working_day) OVER(ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING), 1) = 1 AND working_day = 0 THEN COALESCE(MIN(Date_Home) OVER(ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING), date_home)
ELSE NULL
END AS PrevWorkDay
FROM holiday_calendar
) src
) src
ORDER BY date_home
This assumes your source data is stored in a table called "holiday_calendar".
The COALESCE's are used to handle the first row in the result set, which can't compute values for the previous row, since there is no previous row.
Give it a try and let me know.