Codewars SQL

Kata 5kyu

Count Weekdays

You need to create a function that calculates the number of weekdays (Monday through Friday) between two dates inclusively.

The function should be named weekdays accept two arguments of type DATE and return an INTEGER value.

weekdays(DATE, DATE) INTEGER

The order of arguments shouldn’t matter. To illustrate both of the following queries

SELECT weekdays('2016-01-01', '2016-01-10');
SELECT weekdays('2016-01-10', '2016-01-01');

should produce the same result

weekdays
----------
        6
(1 row)

Solution:

create or replace function weekdays(DATE, DATE) 
returns int as $$
begin
    return count(days)::int
from generate_series(least($1, $2),greatest($1, $2), '1 day')
as days
where extract(DOW from days) NOT IN (0,6);
end;
$$ language plpgsql;

Official Solution:

-- Replace with your code
create or replace function weekdays(_start date, _finish date) 
returns integer
as
$$

  select count(*) filter (where extract(dow from g.d) between 1 and 5)::int as weekdays
  from generate_series(least(_start, _finish), greatest(_start, _finish), interval '1 day') as g(d);

$$ language sql;

Link

Reference