working days between dates

Which function can calculate working days between dates. It is impossible to develop an algorithm. I have no idea how to do this.

DATEDIFF calculates days between two dates:

SELECT DATEDIFF(NOW(), '2019-01-01');

But you want working days?

I study and I received the task in Heidsql, the information is little, and it is very difficult to fulfill it. From January 1 to calculate all working days, or to put the date of May 5, 2020 and to give the order to find out what the date will be if we choose 23 working days.

I study and I received the task in Heidsql, the information is little, and it is very difficult to fulfill it. From January 1 to calculate all working days, or to put the date of May 5, 2020 and to give the order to find out what the date will be if we choose 23 working days.

any date set to calculate the number of working days, we receive the result 282, the calculation is made only from 01.01.20 until today