My favorite function ARRAYFORMULA in Google Spreadsheet

When you input daily or weekly data, you need copy & paste statistical(extracted) data, like below.

For example, using google form and so on.

Because Google forms data should be written at last row's next position, you can not input statistical formula before it wrote.

In my experience, I copy & paste using Google Script by Trigger, yesterday.

But sometime, there are errors in trigger unfortunately.

So, google give great function me. That is ARRAYFORMULA!

ARRAYFORMULA is very good solution at this time.

In first row, you can input formula like below;

=IFERROR(ARRAYFORMULA(IF(D1:D="","",NETWORKDAYS(D1:D,E1:E,'HOLIDAYS'!B1:B))),"소요일정")

This means that calculate working day between start date and end date.

(NETWORKDAYS : https://support.google.com/docs/answer/3092979?hl=ko)

In HOLIDAYS sheet, you can write happy days.

I will input many days the sheet!

ARRAYFORMULA give user write once, for automatic formula.