Add a function to compute the number of business days between two dates

[MrPowers]

See this comment and some of the other comments that follow.

The function should be in functions.py and be called something like business_days_between or something (consistent with this this answer).

[fpvmorais]

Here's a possible solution to calculate:

CREATE FUNCTION IF NOT EXISTS udf_workdays(StartDate date,
                                           EndDate date,
                                           Holidays array<date> array())
RETURNS int
RETURN
(
    REDUCE(
      ARRAY_EXCEPT(SEQUENCE(StartDate, EndDate),Holidays)
      0,
      (acc, x) -> acc + IF(DATE_FORMAT(x, 'E') IN ('Sat', 'Sun'), 0, 1))
);

This UDF can accept an optional list of holidays to exclude besides the weekend days

[robertkossendey]

Thank you for the contribution! But I think we should make it work without an UDF, so that Spark can optimize the query

[puneetsharma04]

@MrPowers : I would like to work on this issue , can you assign this issue to me?

[MrPowers]

This was added!