Kata

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)